Question 439363
    one side of the rectangular area is 20 feet long. i want to fence in a area of 500 sq. ft. how much feet of fencing is needed?
.
Let x = length of remaining side
then since length*width=area
we have
20x = 500
x = 500/20
x = 25 feet
.
fence needed is equal to the perimeter:
2(20+25)
2(45)
90 feet (this is what they're looking for)