Given the following enthalpy change values for the reactions below:

A + B 2C ; _rH = -277.7 kJ mol^-1

E + F C + 2D ; _rH = -257.3 kJ mol^-1

E + G H ; _rH = 325.3 kJ mol^-1

Calculate _rH for the following reaction (in kJ mol^-1) using Hess's Law:

A + B + 4G + 4D 4H + 2F

with step by step