In a circuit shown in Fig. 3.54 resistances R1, and R2 are known, as well as emf's

Question:

In a circuit shown in Fig. 3.54 resistances R1, and R2 are known, as well as emf's ε1, and ε2. The internal resistances of the sources are negligible. At what value of the resistance R will the thermal power generated in it be the highest?
What is it equal to?

62 R1