Calculus 2
posted by Heather .
The pressure P of a gas is related to its volume V by the formula P=k/V where k is a constant. A quantity of gas with an initial volume of 1 cubic meter and a pressure of 2.5 newtons per square meter expands to a volume of 16 cubic meters. Find the work done by the gas.

Please help! I just don't know what to put inside the integral!