An ideal gas in a moveable piston is allowed to reversibly expand by slowly heating at constant

Question

pressure.
a. Derive the equation for the work done reversibly as a function of the initial and final temperatures.( i have used w=-nrtln(v final/v intial) i dont know how can I take derivative.
b. Derive the equation for the change in heat in the system which is q.
c. Derive the equation for the change in entropy.
I am not sure for b and c.