Question

If m and n are positive integers and 2m + 3n = 15, what is the sum of all possible values of m?

Answer 1

2(3)+3(3)=15
6+9=15
15=15
M=3

Answer 2

One can write down all possilities:
 - m =0 , n= 5
 - m cannot take value 1 or 2.
 - m= 3, n= 3
 - m cannot take value 4 or 5
 - m= 6 , n= 1
So the sum 0 + 3+ 6 = 9