Perimeter of a rectangle = 2L + 2W
Perimeter = 39
W = 8.5
we plug those into the perimeter equation and get
2L + 2(8.5) = 39
simplify
2L + 17 = 39
subtract 17 from both sides
2L = 22
divide both sides by 2
L = 11
therefore the length of the sheet of paper is 11 in.
