Answer:
37.5%
Explanation:
We define first our values, that are,
[tex]Q_H=80MW\\Q_c=50MW[/tex]
We can now calculate the net power output, that is
[tex]W=Q_H-Q_c = (80-50) = 30MW[/tex]
Thermal efficiency is given by
[tex]\eta = \frac{W}{Q_H}\\\eta = \frac{30}{80}\\\eta = 0.375\\\eta = 37.5%[/tex]