Answer:
The area is 15 feet
Explanation:
So you are going to need two different equations-
l = w(3)
2l + 2w = 40
Insert the first equation into the second-
2(3w) + 2w = 40
Simplify this equation-
6w + 2w = 40
8w = 40
Divide both sides by 5
w = 5
Solve first equation
l = 5(3)
l = 15
Then find the area-
5 x 15 = 75