计算下面各题,能简便计算的要简便计算 3/7+1/4-13/28 4/5+(7/12+1/5)5-5/17-12/7 4/5-(1/6+3/10)

问题描述:

计算下面各题,能简便计算的要简便计算
3
7
+
1
4
-
13
28
                      
4
5
+(
7
12
+
1
5
5-
5
17
-
12
7
                       
4
5
-(
1
6
+
3
10

(1)

3
7
+
1
4
-
13
28

=
19
28
-
13
28

=
3
14

(2)
4
5
+(
7
12
+
1
5

=(
4
5
+
1
5
)+
7
12

=1+
7
12

=1
7
12

(3)5-
5
17
-
12
7

=4
12
17
-
12
7

=2
118
119

(4)
4
5
-(
1
6
+
3
10

=
4
5
-
7
15

=
1
3