Answer:
A = 10W - W²
Explanation:
Perimeter of a rectangle = 2(L+W)
Area of a rectangle =LW
L is the length
W is the width
Given
Perimeter = 20m
20 = 2 (L+W)
10 = L+W
L = 10 - W ....2
Substitute equation 2 into the formula for calculating the area
Recall that A = LW
A = (10-W)W
A = 10W - W²
Hence the area of the rectangle as a function of the length of ones its side is expressed as A = 10W - W²