If I subtract 2 from my grandfather’s age, the result is divisible by 7. If I subtract 3 from my grandfather’s age, the result is divisible by 5. If I subtract 5 from my grandfather’s age, the result is divisible by 11. How old is my grandfather?
I can answer, there are many way to know but your grandfather's age is almost under 100 and greater than 40. So it belongs to this set {49, 60, 71, 82, 93}. And we have to check two first hints and the answer is 93.
