The area of a rectangle is 63 square inches. The length is 9 inches. What is the measure of its width? Which equation represents this problem? A = Lw

A) 8x = 6; x = 48 in.
B) 6x = 40; x = 4 in.
C) 48x = 48; x = 1 in.
D) 9x = 63; x = 7 in.