The thermal efficiency of the heat engine is

Question

A solar energy based heat engine which receives 80 kJ of heat at 100⁰C and rejects 70 kJ of heat to the ambient at 30⁰C and rejects 70 kJ of heat to the ambient at 305⁰C is to be designed. The thermal efficiency of the heat engine is                                                                            

          (a) 70%                                                               (b) 18.8%

            (c) 12.5%                                                           (d) Indeterminate