1 8.7％×2.5+7.5×0.087 所有的能简算的要简算 2 （7/9+4/15-3/5)×4 3 80％÷[62

1 8.7％×2.5+7.5×0.087
=0.087x(2.5+7.5)
=0.087x10
=0.87

2 （7/9+4/15-3/5)×4
=(35/45+12/45-27/45)x4
=4/9x4
=16/9

3 80％÷[62.5%×（1-20%）]
=0.8÷（0.625x0.8）
=0.8÷0.5
=1.6

4 5/6÷5/12+7/15×3/7
=2+1/5
=2.2

5 25%×3.7+7.3×1/4-25%
=0.25x(3.7+7.3-1)
=0.25x10
=2.5

6 （50％-37.5%）÷75%

=0.125÷0.75
=1/8÷3/4
=1/6

1.原式= (2.5+7.5)* 0.087 =0.87
2.原式= [7/9+(4/15-3/5)]* 4 = (7/9-1/3)*4 = 4/9*4 =16/9
3.原式=80%÷(1-20%)÷62.5% =1/0.625=8/5
4.原式=5/6*12/5 + 1/5 =11/5
5.原式= 0.25* (3.7+7.3-1) =2.5
6.原式=0.5/0.75 -0.375/0.75 = 2/3 -1/2 =1/6

　　1 8.7％×2.5+7.5×0.087=0.087×2.5+7.5×0.087=0.087*（2.5+7.5）=0.87
　　2 （7/9+4/15-3/5)×4 先算4/15-3/5 或者直接硬算
3 80％÷[62.5%×（1-20%）] =80％÷[62.5%×0.8】=62.5%
4硬算
5先减后加同1
6硬算
伙计，要记公式啊.