DETAILS The pressure P of a sample gas is directly proportional to the temperature 7 and inversely proportional to the volume V. (a) Write an equation that expresses this variation. (Use k for the constant of proportionality.) (b) Find the constant of proportionality if 100 L of gas exerts a pressure of 33.6 kPa at a temperature of 300 K (absolute temperature measured on the Kelvin scale). K = (c) If the temperature is increased to 400 K and the volume is decreased to 40 L, what is the pressure of the gas? (Round your answer to one decimal place.) P = kPa