A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered.If the area of the field is 600 sq.ft, how many feet of fencing will be required ? Choose the most appropriate option:
A) 80 feet
B) 70 feet
C) 60 feet
D) 50 feet
E) 20 feet

Rationale: "explanation : we are given with length and area , so we can find the breadth . as length * breadth = area = > 20 * breadth = 600 = > breadth = 30 feet area to be fenced = 2 b + l = 2 * 30 + 20 = 80 feet answer : option a"
Answer: A