Given the following, what would the new volume of the balloon be?

A child has a toy balloon with a volume of 1.80 liters. The temperature of the balloon when it was filled was 20° C 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 and the temperature is -10° C.....