[Khemikooligan]

So I have another problem on my practice test I cant figure out. I have taken a screenshot with two problems but I only need help with the second one (#8).

Image Link: https://i.imgur.com/slov0sV.png



Basically, I don't know what equation to use that can find work with changing volume AND pressure. I found q using q=nCΔT, and I was going to use        w=-P_extΔV to find w, but because the pressure is changing as well I can't use that equation. The answer my Professor gave on his key was 4P₀V₀. Any help would be greatly appreciated.

[mjc123]

I was going to use        w=-PextΔV to find w, but because the pressure is changing as well I can't use that equation.

Why? Theexternal pressure isn't changing.