GMAT prep question

[zozo123]

Can you help me? thanks

[me4mba]

What is the greatest common divisor of positive integers m and n?

(1) m is a prime number
(2) 2n = 7m

Statement 1 is insufficient because it doesn't give us any info about n.

Statement 2 is insufficient because m and n can be any number.

Statement 1&2 together - from (1), we know that m is a prime number. That means that m must be 2 according to (2) because if 7m is equal to 2n, 7m must be a multiple of 2. 7 is prime and doesn't have a 2 in its factor. Thus, m must be 2.

If m is 2, then n is 7 and the greatest common divisor would be 1.