Can Someone please help me with this math question?

This is a PV=nRt equation, but because n, R, & T don't change you can use P1V1=P2V2. P1 is 86 cm Hg and V1 is 200 in3 and P2 is 80 cm Hg. You can do some rearranging of the above equation to get the answer. I won't give you the answer because that's cheating but its not d or a.