Answer:
(40+2b)cm
Step-by-step explanation:
Complete question
Jimmy is putting up a fence around his rectangular garden. One side of the garden is 20 feet long, and b represents the width, How much fencing material will he need.
To get the amount of fencing material needed, we will find the perimeter of the fence
perimeter of the fence = 2(L+W)
L is the length
W is the width
Given
Length = 20feet
Width = b feet
perimeter of the fence = 2(20+b)
perimeter of the fence = 2(20) + 2b
perimeter of the fence = 40+2b cm
Hence the amount of material needed will be (40+2b)cm
