I did by solving the equations, like laxieqv. I did my usual mistake as
x + 4 = 1 as x = 5 instead of x = -3. Surprisingly, I got the answer.
By having x = 5; I got
e = 2
y = -9 (no dependency)
n = -7
z = 8
m = 12
m + n = 5
bsmith75's answer was a smart one.
PS: This post was answered in GMATYahooGroups also.
fresinha12: Could you please tell which software it is?