Question

A and b are two positive integers such that the least prime factor of a is 3 and the least prime factor of b is 5. then calculate the least prime factor of (a+b).
Please answer it briefly. :)

Answer 1

A and b are both odd numbers because their least prime factors are odd. When two odd numbers are added, their sum is even.

The least prime factor of (a+b) is the least even number: 2.

Perhaps I made that too brief for you. Let me know if you need clarification.