A particular power plant operates with a heat reservoir at 350C and a heat sink reservoir at 30C. It has a thermal efficiency equal to 53% of the Carnot-engine thermal efficiency for the same...

A particular power plant operates with a heat reservoir at 350C and a heat sink reservoir at 30C. It has a thermal efficiency equal to 53% of the Carnot-engine thermal efficiency for the same temperatures.

To what temperature must the heat source reservoir be raised to increase the thermal efficiency of the plant to 31%? Again n is 53% of the Carnot-engine value.

whole number , in C.