Answer:
Perimeter = 2 × (length + width) -------(1)
Let width be w
Given length is 20ft longer than width, L = 20 + w
substitute L and w in (1)
perimeter = 2× ( 20 + w + w)
100 = 2 ×(20 + 2w)
50 = 20 + 2w
30 = 2w
w= 15feet
L = 20 + w = 20 + 15 = 35feet
option 1) Â 15 ft by 35ft