Hello everyone,
The creators of this particular maths puzzle said that there are actually 2 correct answers, also only 1 in every 1000 people gets both answers even if they know that there's two different but correct answers to the puzzle, I got both answers relatively quickly so I was happy with that, but I had previously know that there were 2 correct answers.
Anyway, so there you have it, according to the creators there are 2 correct answers for this puzzle, 40 and 96...