An engine takes 4200 J of heat from its hot reservoir each cycle and gives 2940 J to the cold one.

A heat engine takes $Q_h$ from a hot reservoir, does work $W = Q_h - Q_c$ and gives $Q_c$ to a cold one: $\eta = \dfrac{W}{Q_h}$. A refrigerator uses work $W$ to take $Q_c$ from the cold side: $\text{COP} = \dfrac{Q_c}{W}$, and it gives $Q_h = Q_c + W$ to the warm side.