Confused? Let us explain.
Do you want to do a problem involving a hot air balloon? Actually it doesn't matter because you're going to do one.(ignore the fact that it's more of a weather balloon than a hot air balloon... you can thank us later that it's actually on the extra credit though)
A weather balloon containing 450L of helium is sealed at BHS on a rainy day when the pressure is .97 atm and the T is 22 degrees celsius. What is the new volume of the balloon at an altitude of 10,000 feet where P=0.65 atm and T=-4 degrees celsius?