Irreversible less reversible

A no reversible heat engine operates among a high-temperature reservoir at Th = 810 K and a low-temperature reservoir at Tc = 330K. through each cycle the engine absorbs 580 J of heat from the high-temperature reservoir and performs 109 J of work.

a) Compute the total entropy change ΔStot for one cycle.

b) How much work would a reversible heat engine perform in one cycle if it operated among the same two temperatures and absorbed the same amount of heat?

c) Show that the difference in work among the non-reversible engine and the reversible engine is equal to TcΔStot, by calculating both of these quantities.