Find the constant of variation k for the inverse variation. Then write an equation for the inverse variation. y = 5 when x = 3.

The amount of time it takes mail carriers to deliver the mail in one town is inversely proportional to the number of mail carriers delivering the mail. With 28 mail carriers, it takes 7 hours to deliver the town’s mail. What is the number of hours it would take 49 mail carriers to deliver the town’s mail?

An enclosed gas exerts a pressure P on the walls of a container. This pressure is directly proportional to the temperature T of the gas. If the pressure is 9 lb per square inch. when the temperature is 378ºF, find the constant of variation.