Calculate the change in the entropy of nitrogen using both the ideal-gas table and the entropy departure

Question:

Calculate the change in the entropy of nitrogen using both the ideal-gas table and the entropy departure chart if its state changes from:
a) 260 K and 900 kPa to 800 K and 4 MPa
b) 350 K and 1200 kPa to 700 K and 8 MPa
c) 500 K and 1800 kPa to 220 K and 10 MPa