The perimeter it how long it is all the way around, so all of the sides added together.
We know it measures 8 1/2 inches wide, and 11 inches long.
So now we know all of the sides would be 8 1/2+8 1/2+11+11.
8 1/2+8 1/2=17, and 11+11=22, 17+22=39
The perimeter of the typing paper is 39 inches.