18÷2.5 =18x4/(2.5x4)=72/10=7.21.7÷1.25=1.7x0.8/(1.25x0.8)=1.7x(1-0.2)=1.7-0.34=1.365×7/9＋11×5/9=5/9x(7+11)=18x5/9=101.25×4.8×0.75=1.25x0.8x6x3/4=9/2=4.51300÷12.5=1300x8/(12.5x8)=1300x8/100=13x...