问题 解答题
计算下面各题,能简算的要简算.
①2-
2
7
-
5
7
5
8
-(
5
8
-
1
2
4
3
-
1
8
+
7
12
④6-(
3
4
-
2
5
答案

①2-

2
7
-
5
7

=2-(

2
7
+
5
7
),

=2-1,

=1;

5
8
-(
5
8
-
1
2
),

=

5
8
-
5
8
+
1
2

=

1
2

4
3
-
1
8
+
7
12

=

29
24
+
7
12

=

43
24

④6-(

3
4
-
2
5
),

=6-

7
20

=5

13
20

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