Correct answer: 60.6
For a heat engine, efficiency is η = W/Q_in. With W = 50 kJ and η = 0.75, the heat input is 66.7 kJ, so the rejected heat is Q_out = Q_in - W = 16.7 kJ. However, the provided correct option indicates the intended calculation is likely based on a different convention or a typo in the problem statement.