The pressure P of a sample of gas is directly proportional to the temperature T and inversely proportional to the volume V.

a.) Write an equation that expresses this variation.

b.) Find the constant of proportionality if 100 L of gas exerts a pressure of 33.2 kPa at a temperature of 400 K (absolute temperature measured on the Kelvin scale).

c.) If the temperature is increased to 500K and the volume is decreased to 80L, what is the pressure of the gas?