2: 688*0.25+768%200 *60 = 352

3: 688%200*60+768*0.25 = 372

Formula 4: 768%200 *60+688%200*60=360.

Teacher Zhang is more reasonable according to the third plan.

2. Because money between 600 and 800 is 180.

180/0.25=720

So below 720, it will be rolled back, above 720, it will be 75% off, and so will 720.