Amy wants to fence in a yard using 400 feet of fencing. If she wants the yard to be 30-feet wide, how long will it be?
The formula used to determine the perimeter of a rectangle is P = 2(L + W). The width is 30, and the parameter is 400. 400 = 2(L + 30).
400 = 2L + 60
340 = 2L
L = 170