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计算下面各题,怎么简便怎么算.57+58+38+272-(34-25)15-5÷12-71259-(29-15)

题目详情
计算下面各题,怎么简便怎么算.
5
7
+
5
8
+
3
8
+
2
7

2-(
3
4
-
2
5

15-5÷12-
7
12

5
9
-(
2
9
-
1
5
▼优质解答
答案和解析
(1)
5
7
+
5
8
+
3
8
+
2
7

=(
5
7
+
2
7
)+(
5
8
+
3
8

=1+1
=2;
(2)2-(
3
4
-
2
5

=2-
7
20

=1
13
20

(3)15-5÷12-
7
12

=15-
5
12
-
7
12

=15-(
5
12
+
7
12

=15-1
=14;
(4)
5
9
-(
2
9
-
1
5

=
5
9
-
2
9
+
1
5

=
1
3
+
1
5

=
8
15