Two quantities of a gas at a temperature of 62 F are mixed, without chang- ing the temperature, in a container whose volume is 22 cu ft. In their original conditions, the first quantity occupied a volume of 16 cu ft at a pressure of 40 psi absolute, and the second quantity had a volume of 14 cu ft at a pres- sure of 25 psi absolute. What is the gage pressure of the mixture?