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, the least prime factor of (a + b) is

Least prime factor being 3 or 5 means that 2 is not a factor.

So the numbers are both odd.


a + b will be even no. as a is odd and b is odd {∵ odd + odd = even}


Least prime factor of an even no is 2.

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