Hey there!
a) The amount of fencing needed to completely surround the football field is also known as the perimeter. In order to find the perimeter, you can multiply both the length and width by two, because in a rectangle there are four sides.
F = 2w + 2l
b) If the length of the football field is twice its width, that would mean that the length is the width multiplied by two.
l = 2w
c) If w = 12 and l = 20, we would need to use those values and plug them back into our original equation to find the perimeter, or F.
F = 2(12) + 2(20)
F = 24 + 40
F = 64 feet
d) If we have 120 feet of fencing, then that would be our F value in the original equation. And then we would also plug in 30 for our l value. Then, we would solve for the width as normal.
120 = 2w + 2(30)
120 = 2w + 60
2w = 60
w = 30 feet
Hope this helps!! :)
