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1. 口算:
(1)$(-3)+(-4)=$
(3)$(-4)+6=$
(5)$6+(-6)=$
(7)$(-10)+6=$
(9)$(-2.6)+(+1.2)=$
(11)$(-0.9)+(-2.7)=$
(13)$(-\frac {1}{3})+\frac {2}{5}=$
(15)$-2\frac {1}{4}+(-1)=$
(1)$(-3)+(-4)=$
-7
(2)$(-4.7)+3.9=$-0.8
(3)$(-4)+6=$
2
(4)$(-4)+4=$0
(5)$6+(-6)=$
0
(6)$0+(-6)=$-6
(7)$(-10)+6=$
-4
(8)$(+12)+(-4)=$8
(9)$(-2.6)+(+1.2)=$
-1.4
(10)$(-3.2)+(+5.2)=$2
(11)$(-0.9)+(-2.7)=$
-3.6
(12)$(-1.5)+9=$7.5
(13)$(-\frac {1}{3})+\frac {2}{5}=$
$\frac{1}{15}$
(14)$\frac {1}{4}+(-\frac {1}{12})=$$\frac{1}{6}$
(15)$-2\frac {1}{4}+(-1)=$
$-3\frac{1}{4}$
(16)$-\frac {1}{8}+(-0.125)=$$-\frac{1}{4}$
答案：
(1)-7
(2)-0.8
(3)2
(4)0
(5)0
(6)-6
(7)-4
(8)8
(9)-1.4
(10)2
(11)-3.6
(12)7.5
(13)$\frac{1}{15}$
(14)$\frac{1}{6}$
(15)$-3\frac{1}{4}$
(16)$-\frac{1}{4}$
(1)-7
(2)-0.8
(3)2
(4)0
(5)0
(6)-6
(7)-4
(8)8
(9)-1.4
(10)2
(11)-3.6
(12)7.5
(13)$\frac{1}{15}$
(14)$\frac{1}{6}$
(15)$-3\frac{1}{4}$
(16)$-\frac{1}{4}$
2. 计算:
(1)$-12+\frac {1}{7}$; (2)$3.14+(-5.2)$;
(3)$(-4.1)+(-15.61)$; (4)$\frac {3}{10}+(-\frac {2}{5})$.
(1)$-12+\frac {1}{7}$; (2)$3.14+(-5.2)$;
(3)$(-4.1)+(-15.61)$; (4)$\frac {3}{10}+(-\frac {2}{5})$.
答案：
(1)$-11\frac{6}{7}$
(2)-2.06
(3)-19.71
(4)$-\frac{1}{10}$
(1)$-11\frac{6}{7}$
(2)-2.06
(3)-19.71
(4)$-\frac{1}{10}$
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