Answer:
P = 2l + 2w (2 times the length plus 2 times the width)
P = 2(40) + 2(20)
P = 80 + 40
P = 120 ft
You can also add the four sides together. (20 + 20 + 40 + 40
Step-by-step explanation:Since fencing the garden is the measure of perimeter of the garden and length and width of the rectangle are given, we find the perimeter of rectangle which is 2*width +2*length=2*20+2*40=40+80=120 feet of fence are needed.