A child has a toy balloon with a volume of 1.80 L. The temperature of the balloon when it was filled was 20.ºC and the pressure
was 1.00 atm. If the child were to let go of the balloon and it rose 3 km into the sky where the pressure is 0.667 atm, the balloon’s volume becomes 1.55 L. What is the new temperature, in ºC?