Answer:
$1200
Step-by-step explanation:
Let the roof be square shaped
Area of the roof = L²
L is the side length of the roof
Given
L = 40ft
Area of the roof = 40²
Area of the roof = 1600ft²
If plants used for a green roof cost $0.75 per square foot, this means
1 ft² = $0.75
Let the cost needed to cover both sides of the roof be y, hence;
1600ft² = y
Divide both expressions
1/1600 = 0.75/y
y × 1 = 0.75×1600.
y = 0.75×1600
y = 1200
Hence it will cost $1200 to cover both sides of the roof
