Physics/Thermodynamics question. Dont understand it at all, please answer?

A gas initially at 1 MPa, 500°C is contained in a piston and cylinder arrangement with an initial volume of 0.1 m3. The gas is then slowly expanded according to the relation
PV = constant
until a final pressure of 100 kPa is reached. Determine the work for this process.

2) Helium gas expands from 125 kPa, 350 K and 0.25 m3 to 100 kPa in a polytropic process with n = 1.667. How much work does it give out?

What don't you understand?

for the first question the definition of work for a non flow process is defined as:

$W= \int_{V1}^{V2} p dv$

for the second question:

a polytropic process will have the relation:

$PV^n = constant$

now solve!

still not getting the solutuion

post your working, I'll have a look

Thanks a lot for your help, I have made progress

but this is the last question in my book now, on which I am stuck on.
Please guide me if you can on me on this?

A piston cylinder has 1.5 kg of air at 300 K and 150 kPa. It is now heatedup in a two step process. First constant volume to 1000 K (state 2) thenfollowed by a constant pressure process to 1500 K, state 3. Find the finalvolume and the work in the process.