COLLEGE ALGEBRA
posted by BARBARA on .
THE PRIMETER OF SOME TRAFFIC SIGN MUST BE 78INCHES ALSO ITS LENGTH IS 7INCHES LONGER THAN ITS WIDTH
FIND THE DIMENSIONS OF THE SIGN
WHAT IS THE LENGTH
WHAT IS THE WIDTH

What is the shape of the sign?

Assuming the sign is rectangular, your initial formula is
P = 2L + 2W
You know the perimeter is 78 inches so replace P with 78.
78 = 2L + 2W
You know that the length is 7 inches longer than the width.
78 = 2(W + 7) + 2W
Simplify.
78 = 2W + 14 +2W
78 = 4W + 14
Solve for W, the width.
64 = 4W
16 = W
Add 7 to find the length.
16 + 7 = L
23 = L
The length is 23 inches. The width is 16 inches.