Question

能简算的要简算 （3/4-3/5）÷7/10 （2/3+2/9）÷20/21 1-5/14

问题补充：能简算的要简算
（3/4-3/5）÷7/10
（2/3+2/9）÷20/21
1-5/14÷5/7
1/4÷（2/3+1/2）×4/5

Answer 1

(3/4-3/5）÷7/10
=(15/20-12/20)x10/7
=3/20 x 10/7
=3/14

（2/3+2/9）÷20/21
=(6/9+2/9)x21/20
=8/9 x 21/20
=2/3 x 7/5
=14/15

1-5/14÷5/7
=1-5/14 x 7/5
=1-1/2
=1/2

1/4÷（2/3+1/2）×4/5
=1/4÷7/6 x 4/5
=6/28 x 4/5
=6/35

追问

确定对吗?

追答

确定

追问

全死算？

追答

你要把括号外的乘与括号内的先约分？那样也不简单，因为这些数很小，通分很简单，如数字大，宜先约分化简再算加减。

Answer 2

1) =(3/20)*(10/7)=3/14
2) =(6/9-2/9)*(21/20)=(4/9)*(21/20)=7/15
3) =1-(5/14)*(7/5)=1-1/2=1/2
4) =(1/4)*(4/5)/(7/6)=(1/5)*(6/7)=6/35