问题 解答题
计算.
3.2×0.25-
4
7
÷4      
0.4×(3.85-0.4)÷13.8
15.8-
7
18
+14.2-
11
18
      
8×(
3
8
+
1
27
)+
19
27
13
18
÷(
5
6
+
2
3
×
3
8
)     
68÷[0.5×(7.5-0.7)].
答案

(1)3.2×0.25-

4
7
÷4,

=

16
5
×
1
4
-
4
7
×
1
4

=

4
5
-
1
7

=

23
35

(2)0.4×(3.85-0.4)÷13.8,

=0.4×3.45÷13.8,

=1.38÷13.8,

=0.1;

(3)15.8-

7
18
+14.2-
11
18

=(15.8+14.2)-(

7
18
+
11
18
),

=30-1,

=29;

(4)8×(

3
8
+
1
27
)+
19
27

=8×

3
8
+
1
27
×8+
19
27

=3+(

8
27
+
19
27
),

=3+1,

=4;

(5)

13
18
÷(
5
6
+
2
3
×
3
8
),

=

13
18
÷(
5
6
+
1
4
),

=

13
18
÷
13
12

=

13
18
×
12
13

=

2
3

(6)68÷[0.5×(7.5-0.7)],

=68÷[0.5×6.8],

=68÷3.4,

=20.

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