The temperature of source of a Carnot engine of efficiency 20% when the heat exhausted is at 240 k is

What is the temperature of the source in Carnot cycle of 10% efficiency when heat exhaussts at 270 K

Draw a graph between efficiency and the temperature of the source of a Carnot’s engine, when the sink temperature is constant.

The temperature of sink of Carnot engine is 27°C. Efficiency of engine is 25%. Then find the temperature of source.