a helium balloon containing 12m³ of gas at a pressure of 120kPa is released into the air. Assuming that the temperature is constant, calculate the volume of the balloon would have when the pressure inside the balloon has fallen to 40kPa, answer in m³

The average atmospheric pressure on earth is approximated as a function of altitude by the relation patm = 101.325 (1 − 0.02256z)5.256, where patm is the atmospheric pressure in kpa, and z is the altitude in km with z = 0 at sea level. determine the approximate atmospheric pressures at atlanta (z = 306 m), denver (z = 1610 m), mexico city (z = 2309 m), and the top of mount everest (z = 8848 m).