When air expands adiabatically (without gaining or losing heat), its pressure P and volume V are related by the equation PV^{1.4}=C where C is a constant. Suppose that at a certain instant the volume is 500 cubic centimeters and the pressure is 93 kPa and is decreasing at a rate of 15 kPa/minute. At what rate in cubic centimeters per minute is the volume increasing at this instant?

I know that dp/dt=-15

I know that dv/dt=dv/dp dp/dt

I don't know how to use the equation of C in this problem.

Any help is appreciated. Thanks.