The area of room A is (5x2-7x-6) ft2. Room B has an area of (8x2+6x-1) ft2. If room A in the larger room, how much greater is the area of room A than the area of room B?
A. -3x2-x-7
B. 13x2-13x-7
C. -3x2-13x-5
D. 3x2-x-5
We begin by subtracting the area of room B from the area of room A:
$$(5x^2-7x-6)-(8x^2+6x-1)= -3x^2 -13x -5$$
Therefore, the area of room A is $-3x^2-13x-5$ greater than the area of room B, and the answer is $\boxed{\textbf{(C) }-3x^2-13x-5}$.