Calculate the change in enthalpy of air using both the ideal-gas table and the enthalpy departure chart

Question:

Calculate the change in enthalpy of air using both the ideal-gas table and the enthalpy departure chart if its state changes from:
a) 260 K and 900 kPa to 820 K and 4 Mpa
b) 360 K and 900 kPa to 220 K and 8 MPa
c) 300 K and 200 kPa to 600 K and 10 MPa