負數與正數

1)3+(-8)=-5

2)(+11)-(-3)=14

3)(+5)+(-3)=2

4)9-(-4)=13

5)(12)-(-7)=19

6)-5+(-2)=-7

7)(4)+(-7)=-3

8)(-4)+(8)=4

9)(-9)-5=-14

10)(+3)+(-10)=-7

11)(-3)-(-10)=7

12)(-3)-10=-13

13)-5-(-6)=1

14)(-5)-(+6)=-11

15)+5+(-6)=-1

正正得正,負負得正,正負得負,負正得負
1) 3 (-8)
=3-8
=-5
2) ( 11)-(-3)
=11 3
=14
3) ( 3) (-3)
=3-3
=0
4) 9-(-4)
=9 4
=13
5) (12)-(-7)
=12 7
=19
6) -5 (-2)
=-5-2
=-7
7) 4 (-7)
=4-7
=-3
8) (-4) (8)
=-4 8
=8-4
=4
9) (-9)-5
=-9-5
=-14
10) ( 3) (-10)
=3-10
=-7
11) (-3)-(-10)
=-3 10
=10-3
=7
12) (-3)-10
=-3-10
=-13
13) (-5)-( 6)
=-5-6
=-11
14) (-5)-( 6)
=-5-6
=-11
15) 5 (-6)
=5-6
=-1

唔知上面有冇抄錯題目,有既請原諒!!
其實呢D數只要記住最上面果4句就好易明白,如果連正負數都唔掂咁以後D數都好難做!!
希望唔好俾我再見到呢D數出現係YAHOO知識度!
加油!!^^