# It’s the Friday Puzzle!

66

Please do NOT post your answer, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.

I saw a friend of mine the other day.  When I asked him how old he was, he said, “In two years I will be twice as old as I was five years ago.” How old is he?
Oh, and just a quick reminder that I am at the Edinburgh Fringe Festival on Sunday.  Details here (use the code PSYCHOB001 to get a 20% discount).
I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.

## 66 comments on “It’s the Friday Puzzle!”

1. noname says:

• ross says:

finally i got one, friday puzzles had me stumped for a long time

• Anonymous says:

Me too

2. Navneeth says:

Waiting for the puzzle…

3. Elunedb says:

Too easy.. Less than a minute.

4. Tom says:

Had an inkling, verified with simple algebra. Nice and simple in a couple of minutest.

5. Capitan Typo says:

Done-diddly-un

• SilverMarc says:

Hey “Captain” – love your screen name, it made me look back and double-check and of course, I misread the typo at first!

6. Ecohrs197 says:

Only took me about 30 seconds. Thanks though

7. Anonymous says:

I got 27 answers. I believe all of them are right.

• Eddie says:

Do they include complex numbers?

• Anonymous says:

Really?!?

• Eddie says:

8. Andrew says:

One minute to find a pen and paper. Thereafter 10 seconds!

9. Gabriel says:

Got it. This time it took <1 Minute.

10. Stevie says:

Under a minute.

11. Eddie says:

A non-puzzle.

12. Anne Elk says:

For the first time, I can honestly say that this took me less than a minute. Pen, paper, algebra. Tidy, as we say around these parts.

13. DiscoveredJoys says:

About a minute after I remembered my algebra.

Solved. Less than one minute.

Adrian Martienssen – Sent from Samsung Mobile 0…773

Richard Wiseman wrote:

15. postman says:

Someone is sneakily answering it here.

That’s a pretty young friend you have Richard.

16. Anonymous says:

Simple equation! That’s it! took me less than a minute 🙂

17. Uday says:

Simple Equation… That is it.. took me less than a minute

18. issahamati says:

less than two minutes

19. Anonymous says:

Less than 30 seconds using only trial & error

20. less than a minute

21. Pretty tricky actually. My first answer seemed a bit iffy so I tweaked the equation a bit. Let’s see what happens on monday..

22. Baker's Dozen says:

I’m saying nothing.

• Slange Navarr says:

Perhaps ‘cousin’ or ‘nephew’ might have been more appropriate than ‘friend’!

23. Danielle Kennedy says:

Wrote the equation as I read the question, solved within a few seconds.

24. well using algebra – the solution is trivial, but after doing that and rereading the puzzle, it came to me that carefully reading the puzzle, you can solve it rather simply in your head (i know you are still using algebra, but you can take a couple of shirtcuts, that makes it easy to solve in your head)

• Stewart says:

I tried that but it worked out too expensive to replace the cut shirts.

• ChrisR says:

yes, but by the time I’d worked out that I could have done it in my head, I’d done it on paper (and then run it past the question again to ensure I hadn’t missed anything). The number of times I’ve thought “I should be able to do this in my head” and spent ages getting my brain in a knot (or making educated guesses that are anything like) – or missing the question – I tend to go for paper at the first resort

25. Rich B says:

^ exactly what Søren said.

26. Dan says:

Ah Jaysus, if you needed pen and paper to solve that you probably had to ask your mammy for the pen

• Anders says:

In other words you still haven’t solved it, right?

27. Joseph says:

I solved it. It took me only less than 2 mins. I guess to solve it. Simple Algebra 🙂

28. Sue says:

Too easy. Need more of a challenge please.

29. pete says:

I used excel

30. Stewart says:

One minute using schoolchild algebra. Too easy.

31. Had an answer by the time I finished reading the question. then 5 seconds later realised that this was how old they’d be in two years time.

32. mittfh says:

So essentially, we’re looking at (x+2) = 2(x-5)
That wasn’t too hard to solve 🙂

• Slange Navarr says:

Dear mittfh.
Not a big reader, are you, cheese?
SN

33. Steve says:

• mittfh did not post an answer.

• Mr Self Righteous Twat says:

Steve,
My thoughts exactly.
We could practically be identical twins.

• Steve says:

Hey John. I take you point. While an equation is strictly not an answer it near-as-dammit is. Just a trivial solving for x gives the answer. An answer is important, especially the correct one but the working is also important and that is what mittfh essentially gave out. The answer easily follows from that.

34. Anonymous says:

Simple algebra. Less than a minute. I think even my 12 year-old brother could find out the solution to this one!

35. Anonymous says:

Took me less than a minute. Easy algebra is easy.

36. Stephen Fossler says:

Are you ever in Chicago for a show?

Thank you,

Stephen Fossler

Date: Fri, 2 Aug 2013 07:30:33 +0000 To: stephenfossler@hotmail.com

37. Fotoflex says:

Finally one I could solve!
But then in seconds, not minutes.
Is it really that easy, or have I missed something?

38. Dharmaruci says:

i have two solns to quadratic eq. took just a few mins.

39. DeepField says:

This is not a puzzle but a (math) problem. 20 seconds.

• Steve says:

Hi Deepfield (strangely where I live is called Deepfield), I think we had this ‘debate’ before whether a math’s problem is a puzzle or not. http://www.dictionary.com defines a puzzle as: “toy, problem, or other contrivance designed to amuse by presenting difficulties to be solved by ingenuity or patient effort.”. So a problem, maths or otherwise can be a puzzle.

40. Phil H says:

A very simple simultaneous equation. Even after 4 glasses of wine, it only took 4 seconds though I am prone to exaggerate by a factor of 4 when I have had 4 glasses of wine

• Phil H says:

You’re probably wondering. I’ve now had 5 glasses of wine. By how much am I exaggerating? This is better than richard’s puzzle

• Steve says:

Hey Phil. “simultaneous equations” ? It’s not two equations in two unknowns but one equation in one unknown i.e. it’s not a simultaneous equation. Maybe the wine was making you see double ? Maybe you only drank 2 glasses of wine ?

• Dharmaruci says:

steve – as i ans’ed above, is two answers so must be simultaneous eqn. see previous above for more.

• Steve says:

Hi Dharmaruci. Mittfh gave one equation in one unknown above, which is what I had. I’d like to see your simultaneous equations for two solutions. Can you send to me via email ?

• ChrisR says:

Maybe Dharmaruci’s friend is imaginary – but I think not

41. Muaaz Omar says:

It took me a day the answer is ***** can’t wait to see the answer 😥

42. Chakolate says:

Less than a minute. It’s a good thing you didn’t say, “I saw an old friend…”

43. mightyhero says:

Too easy.

• Steve says:

Easy for you and hard for others perhaps. We don’t all have the same ability. Perhaps a different site if this one’s not chanllenging enough. This one http://uktv.co.uk/dave/homepage/sid/9132 is good. TV series was good too.

44. VicinCA says:

Nice one! Took about a minute to freshen the gray matter.
\

45. dayuntoday says:

I love algebra. Simple, but not immediate. I had to get a pencil and paper, and then it only took half a minute.