What is reversible process in thermodynamics?

10) This is a thermodynamics question! I would appreciate any help you could give me! Just make sure your answers are in the correct units and that steps are clear and decisive! Please and thanks!

"An engine manufacturer makes the claim that the engine they have developed will, on each cycle, take 100 J of heat out of boiling water at 100°C, do mechanical work of 80 J, and exhaust 20 J of heat at 10°C. What, if anything, is wrong with this claim?"     The heat exhausted must always be greater than the work done according to the second law of thermodynamics.     This engine violates the first law of thermodynamics because 100 J + 20 J ? 80 J.     An engine would operate by taking in heat at the lower temperature and exhausting heat at the higher temperature.     The efficiency of this engine is greater than the ideal Carnot cycle efficiency.

Is it theoretically possible to devise a heat engine which will create no thermal pollution?