Determine the enthalpy change h of oxygen, in Btu/lbm, as it is heated from 800 to 1500

Question:

Determine the enthalpy change ∆h of oxygen, in Btu/lbm, as it is heated from 800 to 1500 R, using
(a) The empirical specific heat equation as a function of temperature (Table A–2Ec),
(b) The cp value at the average temperature (Table A–2Eb), and
(c) The cp value at room temperature (Table A–2Ea).