Solution: (1) Let the original sales price be X yuan per kWh,
According to the meaning: 40×(x+0.03)+60×(x-0.25)=42.73.
Solution: x=0.5653
∴ When x=0.5653, x+0.03 = 0.5953; x-0.25=0.3 153。
A: The electricity consumption of Xiaoming's home this month is 0.5953 yuan per kilowatt hour in the flat section and 0.3 153 yuan in the valley section.
(2) 100×0.5653-42.73= 13.8.
Answer: If the time-of-use electricity price is not used for settlement, Xiaoming's family will pay more in May 13.8 yuan.
Hope to be adopted!