a substance has constant heat capacity cp 35r

Question

A substance has constant heat capacity C_P = 3.5R and its equation of state is given by:

P (V-cRT) = RT

where c = 5 * 10^-7 m³ /J. This substance is isentropically compressed from P₁ =1 bar, T₁= 300 K to P₂= 5 bar. What is the temperature after compression?

(An "isentropic process" is one in which the entropy of the fluid remains constant.)