1、(68-100x0.5)÷0.4+100
=18÷0.4+100
=45+100
=145(千瓦时)
2、100x(0.5-0.48)/(0.48-0.4)+100
=25+100
=125(千瓦时)
应交电费为:
125x0.48=60(元)