题目内容

3
5
+
2
5
=
7
15
-
2
15
=
1
2
+
1
3
=
1
2
+4=
1-
7
9
=
1
3
+
1
4
=
1
2
+
5
6
=
1
7
+
1
8
=
分析：同分母分数相加减，分子不变，分母相加减；
异分母分数相加减，先通分，变成同分母的分数相加减，再计算．
解答：解：
3
5
+
2
5
=1，
7
15
-
2
15
=
1
3
，
1
2
+
1
3
=
5
6
，
1
2
+4=4
1
2
，
1-
7
9
=
2
9
，
1
3
+
1
4
=
7
12
，
1
2
+
5
6
=
4
3
，
1
7
+
1
8
=
15
56
．
点评：本题属于基本的计算，在平时都积累经验，逐步提高运算的速度和准确性．
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相关题目
直接写出得数．
3
5
+
2
5
=
7
9
-
5
9
=
7
15
-
2
15
=
1
2
+
1
2
=
1-
3
7
=
1
12
+
5
12
=
1
5
-
1
5
=
4
5
-
2
5
=
6-
2
7
=
3
4
+
2
4
=
9
8
-1=		 2+
2
3
=
解方程．
3
10
+x=
3
5
 x-
7
15
=
1
5
4
9
-x=
1
18
x-
1
10
-
2
5
=
2
5
 3x-
1
7
=5
6
7
 2x+
1
6
=1
1
6
．
3
5
-
2
5
×
3
4
；    36×
4
9
+
1
3
；  
4
5
+
7
15
×
4
7
；    
3
8
×
4
5
-
7
30
；   (
3
4
+
2
5
)×
5
12
；    24×(
5
6
-
5
8
)．
口算
1
4
×
1
3
=
4
7
÷2=
1
2
÷
1
2
=		 10÷
5
6
=
2
3
×
3
4
=
9
10
÷
1
5
=
1
6
÷6=
8
9
÷4=		 15×
4
5
=		 15÷
1
3
=
3
4
×
2
9
=
2
3
÷
1
2
=
2
5
×
1
2
=
1
2
÷
1
4
=
1
2
×
1
4
=
4
5
÷
1
5
=
3
7
×14=
1
4
÷
1
2
=
1
2
-
1
4
=
4
9
×
3
4
=
5
8
×
2
5
=
1
6
÷
2
3
=
1
2
+
1
4
=
3
5
÷1=
7
15
×5=		 1÷
3
4
=
1
2
÷
1
4
=		 1÷
3
5
=
3
4
×12=
1
5
÷
2
3
=
7
9
×
3
7
=		 1-
3
5
=		 18×
5
6
=		 7÷
7
5
=
1
3
+
1
6
=		 1+
3
5
=
2
9
×
1
4
=
8
3
÷2=
3
5
÷
2
5
=
5
9
÷3=
5
6
×
3
10
=
2
5
÷
1
2
=
8×
1
4
=		 9÷
3
4
=		 30×
1
3
=
4
5
÷2=
5
24
÷
5
6
=
5
8
×
1
2
×0=
1
3
×
3
11
=		 8÷
1
4
=
9
10
÷
3
5
=		 0÷
1
3
÷
1
2
=		 1×
9
11
=
2
5
÷
1
5
=
1
3
÷
1
3
=		 0×
2
9
÷
1
2
=
5
6
×
6
5
=
1
5
÷
1
3
=		 0÷
5
12
=		 1×
1
2
÷
1
2
=

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