问题 解答题
计算.(写出解答过程,能应简便方法的要用简便方法)
(1)28×
4
7
×
3
4
(2)(
3
4
-
2
5
)×40
(3)[12×(
1
2
-
1
3
)]÷
3
5
(4)
7
15
×
4
5
+
7
15
÷5.
答案

(1)28×

4
7
×
3
4

=28×(

4
7
×
3
4
),

=28×

3
7

=12;

(2)(

3
4
-
2
5
)×40,

=

3
4
×40-
2
5
×40,

=30-16,

=14;

(3)[12×(

1
2
-
1
3
)]÷
3
5

=[12×

1
2
-12×
1
3
3
5

=[6-4]÷

3
5

=2÷

3
5

=

10
3

(4)

7
15
×
4
5
+
7
15
÷5,

=

7
15
×
4
5
+
7
15
×
1
5

=

7
15
×(
4
5
+
1
5
),

=

7
15
×1,

=

7
15

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