A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered.If the area of the field is 400 sq.ft, how many feet of fencing will be required ?
Pick one.
A) 60 feet B) 50 feet C) 40 feet D) 30 feet E) 5 feet

Rationale: "explanation : we are given with length and area , so we can find the breadth . as length * breadth = area = > 20 * breadth = 400 = > breadth = 20 feet area to be fenced = 2 b + l = 2 * 20 + 20 = 60 feet answer : option a"
Answer: A