2.5×32×12.5 =(2.5×4)×(8×12.5) =10×100 =1000 7/9÷11/5+2/9×5/11 =7/9×5/11+2/9×5/11 =(7/9+2/9)×5/11 =1×5/11 =5/11 3/5÷【(1/5+1/3)÷2/9】 =3/5÷【8/15÷2/9】 =3/5÷12/5 =1/4 678-192÷8×12 =678-24×12 =678-288 =390 8×(7/8-5/9)×9 =8×7/8×9-8×5/9×9 =63-40 =23 2.解方程或解比例。 3/4X+X=1.4 解:1.75X=1.4 X=1.4÷1.75 X=0.8
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