Ok so you will be finding the perimeter of this rectangle. The formula is P(perimeter)=2L(length) + 2W(width)
so the length is 48 and the width is 1/2 of 48, and we all know that 1/2 of 48 = 24 right? so in the formula is says 2L so we will take 48 and multiply it by 2 and get 96. The same way with the width. 24 times 2 = 48 so then we add them together and get 144. Therefore the perimeter and the length of fringe that she will use (or how ever you say it) will be 144 inches.
