Boyle's Law states that when a sample of gas is compressed at a constant temperature, the pressure P P and volume V V satisfy the equation P V = C PV=C, where C C is a constant. Suppose that at a certain instant the volume is 1000 cm 3 1000 cm3, the pressure is 80 kPa 80 kPa, and the pressure is increasing at a rate of 40 kPa/min 40 kPa/min. At what rate is the volume decreasing at this instant?