Understanding PV Diagrams - Work

[tizzful]

Homework Statement

Calculate the work done by the gas during process 1-> 3-> 6.
Express your answer in terms of Po and Vo.

Homework Equations

W=integral(pv) from V1-V2
W=PVln(V2/V1)

The Attempt at a Solution

3Po*V*ln(3Vo/Vo)

I'm not sure what I'm doing wrong, it keeps telling me I'm off by a multiplicative factor.. Should I be using W=nRT ln(V2/V1) ?
ht tp://i33.photobucket.com/albums/d53/tizzful/151890.jpg (take out the space)

 

[tizzful]

Never mind, I solved it