Question

計(jì)算并寫出主要過程．
①

7

10

+

8

15

                         
②

7

16

-

3

20

                        
③

5

24

÷

7

36

．

Answer 1

分析：①②先通分再相加減；③根據(jù)除以一個(gè)數(shù)等于乘這個(gè)數(shù)的倒數(shù)求解．

解答：解：①

7

10

+

8

15

=

21

30

+

16

30

=

21+16

30

=

37

30

；

②

7

16

-

3

20

=

35

80

-

12

80

=

35-12

80

=

23

80

；

③

5

24

÷

7

36

，
=，
=

15

14

．

點(diǎn)評：異分母分?jǐn)?shù)相加減先通分化成同分母分?jǐn)?shù)再計(jì)算；分?jǐn)?shù)除法：除以一個(gè)數(shù)等于乘這個(gè)數(shù)的倒數(shù)求解．