I believe that would be '59'.
59
59 - 2 = 57
158 is the sum of the greatest and smallest prime numbers between 60 and 97.
160
2
97 + 61 = 158
53
The greatest factor of a number is the number itself. So, the greatest factor of 60 is 60.
29 + 31 = 60
It is 1 because 17 is a prime number
A prime number is a number that is only divisible by itself, and 1. The largest prime number below 20 is 19. The smallest prime number above 60 is 61. So the answer will be 19 + 61 = 80
53, 59