One value asks the power plant. If the number in question (2) can be used, the value of a can be found.

(2)

Let's assume that the electricity fee for the excess part is X yuan per kWh, and make an equation.

(80-A)X+ 10=25

(60-A)X+ 10= 15

The solution is A=50 degrees and X=0.5 yuan.

The electricity bill in May is

(125-50) × 0.5+10 = 47.5 yuan.