hello, i am trying to calculate the volume of a balloon (which is quite large). It has been filled with helium via a valve connecting helium storage tanks to the balloon. The knowns I have are the volume of the storage tanks, the intital pressure in the tanks, and the final pressure in the tanks after filling the balloon. I am confident there are enough knowns here to solve this problem and my gut feeling is that its a pretty straightforward solution too. despite this, i cannot seem to solve it.