Subtract what Megan ate from the whole.
4/4-3/4 = 1/4.
Megan did not eat 1/4th of the cookie
Surface area = area of 2 triangular sides + area of the roof + area of the base.
= 2 * 1/2 * 6 * 4 + 2 * 5*7 + 6 * 7
= 24 + 70 + 42
= 136 units^2
A, B, and D? I chose those 3 because they all feature the expression a. (I literally just signed up, sorry, I'm still kind of new.)