问题 解答题
解方程或比例.
36
48
=
x
20
14.2-
2
5
x=4.5
3
7
2
7
=
4
7
:x
答案

(1)

36
48
=
x
20

48x=36×20,

48x÷48=720÷48,

x=15;

(2)14.2-

2
5
x=4.5,

14.2-

2
5
x+
2
5
x=4.5+
2
5
x,

14.2=4.5+

2
5
x,

14.2-4.5=4.5+

2
5
x-4.5,

9.7=

2
5
x,

9.7÷

2
5
=
2
5
2
5

x=24.25;

(3)

3
7
2
7
=
4
7
:x,

3
7
x=
2
7
×
4
7

3
7
3
7
=
2
7
×
4
7
÷
3
7

x=

8
21

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