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.
The other day my friend sent me this note:
‘I’ve changed the calibration dial on my bathroom scale, and so the readings are off by a consistent amount. When I am on the scale it reads 170 pounds, and when my wife is on it, it reads 130. When we stand on it together the scale reads 292 pounds. How should I adjust the scale?’