I had given this link earlier. But here it is again. You need to follow the principle in the table

https://www.visualmathlearning.com/ex_ga ... table.html

so for e.g 4 + X = 1 so X = -5

then, e + (-5) = 7, so e = 12. This way u get the values for all the variables in the table

F = 7, y = -9, n = 3, Z = -2 and M = 2

so M + N = 5

Though there are many variables just do a step by step equation. It will not take time once u know the principle.

Thanks ri 2007, I get it now..though it seems a bit obscure for a GMAT question...

its pretty simple....all the numbers in white squares are the sum of corressponding numbers in yellow. For eg: 1=x+4, -5=y+4 etc.....

So m+n = (z+4) + (y+e) = (z+e) + (y+4) = 10 + -5 = 5.....

GMAT always try to trick the test takers stating simpple pblms in complex figures, statements, matrices etc. We need to carefully see what exactly is GMAT asking. Try to brk the complex statements into simple equations, trim the junk part and take only the essence...

thanx jangojess for clearing the air...this prob stumped me, too. But unless one know the principle of sum table, one can not solve it..thanx again