Question

Wilson cuts rectangular mats for picture frames. The area of the mat before it is cut is represented by the function M(x) = 4x2 + 22x + 30. The area that is cut out and removed from the middle of the mat is represented by the function N(x) = x2 + 7x.

If x is the width of the portion of the mat that is cut out, which function best describes A(x), the area of the cut mat?
A(x) = 4x2 + 21x + 23

A(x) = 3.9x2 + 22x + 23

A(x) = 3x2 + 15x + 30

A(x) = 5x2 + 29x + 30