you can go through the solution of vaishali. and for any doubt you can ask.you have to know these types of partial derivative in thermodynamics. and also remember all Maxwell's equ...
dear, look S is the function of T,V so when you do partial derivative of S then you get dT and dV so TdS/dT at constant V is Cv and dS/dV=dP/dT (according to Maxwell equation)....