The efficiency of an engine is given by:
[tex]\eta = 1 - \frac{T_c}{T_h} [/tex]
where
[tex]T_c[/tex] is the temperature of the cold sink
[tex]T_h[/tex] is the temperature of the heat source
In our problem, [tex]T_c=135 K[/tex] and [tex]T_h=325 K[/tex], so if we substitute these numbers into the equation, we find the efficiency of the engine:
[tex]\eta=1- \frac{135 K}{325 K}=0.585 [/tex]
