1、7/25×4/9+7/25×5/9

=7/25×(4/9+5/9)

=7/25×1

=7/25

2、60×(1/12+1/15+1/4)

=60×1/12+60×1/15+60×1/4

=5+4+15

=24

3、(5/12-3/8)×72

=5/12×72-3/8×72

=30-27

=3

4、6/7-5/24÷7/12

=6/7-5/24×12/7

=12/14-5/14

=7/14

=1/2

5、[3/4×(7/16-1/4)]÷9/13

=3/4×（7/16-4/16）×13/9

=1/4×3/16×13/3

=13/64

6、2/3-7/8+1/3

=(2/3+1/3)-7/8

=1-7/8

=1/8

7、5/6-(3/7-1/6)

=(5/6+1/6)-3/7

=1-3/7

=4/7

8、1-1/3-2/3

=1-(1/3+2/3)

=1-1

=0

9、1+3/5-1/10

=1+6/10-1/10

=1+1/2

=1又1/2

10、3/8-12/13+5/8

=3/8+5/8-12/13

=1-12/13

=1/13

11、1-(1/2-3/4)

=1+3/4-2/4

=1+1/4

=5/4

12、1-1/2-1/4

=1/2-1/4

=2/4-1/4

=1/4

13、2/7-8/9+5/7

=(2/7+5/7)-8/9

=1-8/9

=1/9

14、2-1/4-3/4

=2-(1/4+3/4)

=2-1

=1

15、1/2-(3/8-1/2)

=1/2+1/2-3/4

=1-3/8

=5/8

16、2.64×1.7-2.64×0.7

=2.64×(1.7-0.7)

=2.64×1

=2.64

17、31.5×1.07-3.15×0.7

=3.15×10.7-3.15×0.7

=3.15×(10.7-0.7)

=3.15×10

=31.5

18、2.7×5.7-2.7+5.3×2.7

=2.7×(5.7-1+5.3)

=2.7×10

=27

19、0.625÷0.125×0.8

=(0.625×0.8)×8÷(0.125×8)

=0.5×8÷1

=4

20、18.6×6.1+3.9×18.6

=18.6×(6.1+3.9)

=18.6×10

=186