The heat-removal factor (F_{R}) permits solar collector delivery to be written as a function of collector fluid

Question:

The heat-removal factor $F_{R}$ permits solar collector delivery to be written as a function of collector fluid inlet temperature $T_{f}$ in Equation 7.46. Derive the expression for a factor analogous to $F_{R}$, relating collector energy delivery to fluid outlet temperature.

Equation 7.46