Arectangular field has a perimeter of 500m and an area of 14400m2. find the lengths of the sides

If the rectangle was a square with four equal sides then they would each be 125-m. But 125 x 125 does not equal 14,400. What I did next was lay out the side lengths of what I knew the lengths would be if this rectangle was a square. I did this like this: 125 125 125 125. Next I would take away an equal amount from each outer numbers and added it to the inner numbers and would see if the new set would could get the are of 14,400-m2. Kind of like guess and check. I went through a couple options until I got to this: 90 160 160 90. I multiplied 90 by 160 and it equaled 14,400! Just the are needed! So the side lengths of the rectangle are 90-m, 90-m, 160-m, and 160-m. I hope you can understand what I did! 

Ithink the answer is c just trying to others