Question

Looking for an equation for my joint variation problem.
"The amount of paint needed to cover the walls of a room varies jointly as the perimeter of the room and the height of the wall. If a room with a perimeter of 40 feet and 8-foot walls requires 3.2 quarts of paint, find the amount of paint needed to cover the walls of a room with a perimeter of 45 feet and 8-foot walls."