hello
i used this formula
G1 + G2 + N - B =total

10 + 65 -B = 150

75-B=150

B = 75

therefore 75/150 * 100 is the total % of men across both groups.

i chose c, why is this wrong

Hey TJ,

The problem with this formula is that 150 is the total number of PEOPLE, whereas 10 and 65 only represent the total number of MEN. Because we don't know the total number of men, we can't set up a A + B - Both = Total calculation.

Keep in mind that Data Sufficiency questions are more about logic than they are about math. In high school, your main job was to determine where to put the numbers in "the formula". Because the GMAT is preparing you for graduate school, it's more about your ability to determine whether the formula even applies. Here, because some values are in terms of one group (men) and some in terms of another (people), the formula just doesn't apply, and that's what they're testing.