We can use L, W, and P to represent the rectangle's Length, Width, and Perimeter in units of feet. We know that the perimeter is the sum of the lengths of all the sides.
P = L + W + L + W
P = 2(L + W)
We are told in the problem statement that
L = 2W + 1
P = 20
We can substitute these into the above equation for perimeter to get
20 = 2((2W+1) + W)
10 = 3W+1 (divide by 2, collect terms)
9 = 3W (subtract 1)
3 = W (divide by 3)
L = 2(3)+1 = 7 (use the formula for L to find L from the value of W)
The rectangle is 7 feet long and 3 feet wide.
P = L + W + L + W
P = 2(L + W)
We are told in the problem statement that
L = 2W + 1
P = 20
We can substitute these into the above equation for perimeter to get
20 = 2((2W+1) + W)
10 = 3W+1 (divide by 2, collect terms)
9 = 3W (subtract 1)
3 = W (divide by 3)
L = 2(3)+1 = 7 (use the formula for L to find L from the value of W)
The rectangle is 7 feet long and 3 feet wide.