问题 解答题
求未知数.
4×1.5+8x=72
x+40%x=7.2
2
3
x+
1
2
=3
5-
2
3
x=
1
3
答案

(1)4×1.5+8x=72,

6+8x=72,

6+8x-6=72-6,

8x=66,

8x÷8=66÷8,

x=8.25;

(2)x+40%x=7.2,

1.4x=7.2,

1.4x÷1.4=7.2÷1.4,

x=

36
7

(3)

2
3
x+
1
2
=3,

2
3
x+
1
2
-
1
2
=3-
1
2

2
3
x=
5
2

2
3
x÷
2
3
=
5
2
÷
2
3

x=

15
4

(4)5-

2
3
x=
1
3

5-

2
3
x+
2
3
x=
1
3
+
2
3
x,

2
3
x+
1
3
=5,

2
3
x+
1
3
-
1
3
=5-
1
3

2
3
x=
14
3

2
3
x÷
2
3
=
14
3
÷
2
3

x=7.

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