问题 解答题
(1)已知
6.4
x
=0.12:1.5,求X.
(2)5X+5×2.4-x=18.48
(3)(1
1
2
-
1
5
+
3
8
)-(
3
8
+
4
5
(4)2008÷2008
2008
2009
(5)(9
2
7
+7
2
9
)÷(
5
7
+
5
9
(6)
1
3
+
1
15
+
1
35
+
1
63
+
1
99
+
1
143
答案

(1)

6.4
x
=0.12:1.5,

0.12X=6.4×1.5,

0.12X=9.6,

0.12X÷0.12=9.6÷0.12,

X=80;

(2)5x+5×2.4-x=18.48,

4x+12=18.48,

4x+12-12=18.48-12,

4x=6.48,

4x÷4=6.48÷4,

x=1.62;

(3)(1

1
2
-
1
5
+
3
8
)-(
3
8
+
4
5
),

=1

1
2
-
1
5
+
3
8
-
3
8
-
4
5

=1

1
2
-(
1
5
-
4
5
)+(
3
8
-
3
8
),

=1

1
2
-1-0,

=

1
2

(4)2008÷2008

2008
2009

=2008÷

2008×2009+2008
2009

=2008÷

2008×(2009+1)
2009

=2008÷

2008×2010
2009

=2008×

2009
2008×2010

=

2009
2010

(5)(9

2
7
+7
2
9
)÷(
5
7
+
5
9
),

=16

32
63
÷
80
63

=16

32
63
×
63
80

=(16+

32
63
)×
63
80

=16×

63
80
+
32
63
×
63
80

=

63
5
+
2
5

=13;

(6)

1
3
+
1
15
+
1
35
+
1
63
+
1
99
+
1
143

=

1
1×3
+
1
3×5
+
1
5×7
+
1
7×9
+
1
9×11
+
1
11×13

=

1
2
×(1-
1
3
+
1
3
-
1
5
+
1
5
-
1
7
+
1
7
-
1
9
+
1
9
-
1
11
+
1
11
-
1
13
),

=

1
2
×(1-
1
13
),

=

1
2
×
12
13

=

6
13

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