A rectangular field is to be fenced on three sides, leaving the 20-foot length unfenced. If the area of the field is 680 square feet, how many feet of fencing will be required?

Question: A rectangular field is to be fenced on three sides, leaving the 20-foot length unfenced. If the area of the field is 680 square feet, how many feet of fencing will be required?

Solution:
Given that,
Area of the rectangular field = 680 sq. ft.
One side left unfenced = 20 ft.
Since the uncovered side is one length of the rectangle,
Length = 20 ft

We know,
Area = Length × Width
⇒ 680 = 20 × Width
⇒ Width = 680/20
∴ Width = 34 ft

The field is fenced on three sides only,
∴ Required fencing = Length + 2 × Width
= 20 + 2 × 34
= 20 + 68
= 88 ft