A pulley reduces the effort needed to lift heavy objects. If an object weighs 80 kg, it will weigh only 40 kg when two pulleys are used. Let k be the actual weight of an object, let x be the number of pulleys, and let y be the weight felt by the person using the pulleys. We can model this situation with the inverse variation y = k/x. If the weight of an object is 80 kg, what is the value of y when four pulleys are used?