# Efficiency of sequential Carnot engines [closed]

A Carnot engine A operates between temperature $$T_1$$ and $$T_2$$ ($$T_1>T_2$$). A second Carnot engine B uses all the heat rejected by A as input and input and operates between temperature $$T_2$$ and $$T_3$$ ($$T_2>T_3$$). What will be the efficiency of the coupled engine system ?

It should be the same as one Carnot engine operating between $$T1$$ and $$T3$$.