Given:
Room temp: 293 K
Barometric Pressure: 765 mmHg
Vapor of water: 16.5 mmHg
Volume of O2 collected: 52 mL
Density of H2O2: 1.01 g/mL
% composition of H2O2: 3.02%
Volume of H2O2 used: 5 mL
Volume of O2 collected for unknown solution: 19 mL

Calculate corrected barometric pressure.
I got around 748, don't know if it is correct.

Calculate moles of O2 using the information of density, percent composition, and volume used.
I got 0.02 moles. Don't know if that's right either. Not sure how to incorporate density into finding the moles of H2O2 first, and when I plug it back into the equation, it doesn't make sense.

How do you calculate the percent composition of the unknown?
The information mostly above is for the given, and I have legitimately no idea how to calculate the unknown.

Help is appreciated!