初一代數!!正負數!

1) (-5)+21+(-13)+(+12)
=16-13+12
=15

2) 3.2+(-6.7)+2.15+(-1.5)
=3.2-6.7+2.15-1.5
=-2.85

3) 3+(-1.7)+(-0.25)+0.75+(2.3)
=3-1.7-0.25+0.75+2.3
=4.1

4) -12+8-10+19
=5

5) (-7)-(-10)-(+6)-(-4)-(+10)+(-4)
=-7+10-6+4-10-4
=-13

6)- 4.8+3-2.2-6.4+10.4-3.2
=-3.2

1)(-5)+21+(-13)+(+12)=?
=16-13+12
=15

2)3.2+(-6.7)+2.15+(-1.5)=?
=3.2-6.7+2.15-1.5
=-2.85

3)3+(-1.7)+(-0.25)+0.75+(2.3)=?
=3-1.7-0.25+0.75+2.3
=4.1

4)-12+8-10+19=?
=5

5)(-7)-(-10)-(+6)-(-4)-(+10)+(-4)=?
=-7+10-6+4-10-4
=-13

6)-4.8+3-2.2-6.4+10.4-3.2=?
=-3.2

*Remarks:凡計任何Direction number都要記住一個口號:
正加正等於正
負加負等於正
正加負等於負
負加正等於負

計呢啲數就會好似計普通嘅數咁簡單嫁炸^^
努力!!!希望對你有幫助啦^^

1)(-5)+21+(-13)+(+12)=?
=16-13+12
=15//
2)3.2+(-6.7)+2.15+(-1.5)=?
=3.2-6.7+2.15-1.5
=-2.85//
3)3+(-1.7)+(-0.25)+0.75+(2.3)=?
=3-1.7-0.25+0.75+2.3
=4.1//
4)-12+8-10+19=?
=5//
5)(-7)-(-10)-(+6)-(-4)-(+10)+(-4)=?
=-7+10-6+4-10-4
=-13//
6)-4.8+3-2.2-6.4+10.4-3.2=?
=-3.2 //

1)(-5)+21+(-13)+(+12)=?
=16-13+12
=15

2)3.2+(-6.7)+2.15+(-1.5)=?
=3.2-6.7+2.15-1.5
=-2.85

3)3+(-1.7)+(-0.25)+0.75+(2.3)=?
=3-1.7-0.25+0.75+2.3
=4.1

4)-12+8-10+19=?
=5

5)(-7)-(-10)-(+6)-(-4)-(+10)+(-4)=?
=-7+10-6+4-10-4
=-13

6)-4.8+3-2.2-6.4+10.4-3.2=?
=-3.2