Simple explanation of Boyle's and Charle's law

[dcrickerson]

Nice simple explanation. Good video as always GFM.

[Jeff_S...]

This reminds me of a question I have seen come up on some of my certifications and I'm never sure if I get it right or wrong:

A tank of R-22 is stored at 90 F and is 80% full, what is the pressure of this tank?

I always just used the PT chart and considered the addition of '80% full' as just a full tank, if I remember my EPA test correctly, 80% is the maximum fill level for refrigerant tanks.

Is there more to it, or is the PT chart the correct way to answer that question?