①1÷0.25-0.25÷1
②6.28÷1.25÷8
③25.2÷[14.2-(7.2+2.8)]
④79-18.9÷0.4
⑤4.8×12-4.8×2
⑥4.82÷0.25+1.25÷0.25
4800÷600 420÷35 540÷36
①2800÷35
②2300÷25
③2250÷15
11.11×6666+7778×33.33