math/algebra
posted by jeanne .
the length of a rectangular frame is 5 cm more than the width. the area inside the frame is 66 square cm. find the width of the frame.

L = W + 5
A = L * W
( W + 5 ) * W = 66
W ^ 2 + 5 W = 66
W ^ 2 + 5 W  66 = 0
Solutions of equation are :
W =  11
and
W = 6
Length can't be negative so :
W = 6 cm
Proof:
L = W + 5 = 6 + 5 = 11
A = L * W = 11 * 6 = 66 cm ^ 2