问题 解答题
求未知数x:
(1)
5
6
X+
4
9
×
3
8
=
16
9

(2)75%X-
2
7
X=
39
4

(3)X:1.25=0.4:
3
2
答案

(1)

5
6
X+
4
9
×
3
8
=
16
9

5
6
X+
1
6
=
16
9

5
6
X+
1
6
-
1
6
=
16
9
-
1
6

5
6
X=
29
18

5
6
6
5
=
29
18
×
6
5

X=

29
15

(2)75%X-

2
7
X=
39
4

3
4
-
2
7
)X=
39
4

13
28
X=
39
4

13
28
28
13
=
39
4
×
28
13

X=21;

(3)X:1.25=0.4:

3
2

3
2
X=1.25×0.4,

1.5X=0.5,

1.5X÷1.5=0.5÷1.5,

X=

1
3

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