Answer: Choice B) 17.5 feet
A = Area of rectangle
L = length
W = width
The formula to use is A = L*W, so we multiply length and width.
We know W = 7 but we don't know what L is.
We know that A = 122.5 is also given
So let's solve for L
A = L*W
L*W = A
L*7 = 122.5 plug in the given values
7*L = 122.5
7*L/7 = 122.5/7 divide both sides by 7
L = 17.5
He should cut 17.5 feet of streamer. Keep in mind that this only applies if Adrian wants to make the streamer completely taut and a straight line across the ceiling/wall. If he wants the streamer to hang down a bit (forming a shape like a rope bridge in a sense), then the streamer's length will have to be a bit longer to account for the extra distance along the curve.
