Chemistry Help Please!?

Question

The following experiment is used to determine the amount of helium gas in the container. In the experiment
V = 4.200 L
h = 349 mm.
t = 26° C
Pbar = 755 torr.
Determine the following for the helium gas:
a). Pressure of helium
b). n (number of moles of helium)
c). m (molar mass)
I did it but I didn't do something right...

Answer 1

What answer did you get for those?