〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕

-4
__
12
3

〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕
= (8-20) / 12
= -12 / 12
= -1

〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕
=〔(+8)-(+20)〕÷(+12)
圖片參考：http://hk.yimg.com/i/icon/16/49.gif

=(-12)÷(+12)
圖片參考：http://hk.yimg.com/i/icon/16/26.gif

=(-1)

〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕

(-4)(-5)=20 (負負得正)
(-4)(-3)=12 (負負得正)

((+8)-(+20))÷12
-12÷12
=-1

〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕
=〔(+8)-(20)〕÷〔12〕
=〔8-20〕÷12
=-12÷12
=-1

***記住要點***
1. 先拆括號(由細至大)
2. 負正得負, 負負得正, 正正得正
3. 先乘除後加減

〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕
=〔+8+4(-5)〕÷〔(-4)(-3)〕
=+12x(-5)÷〔(-4)(-3)〕
= -12x5÷〔(-4)(-3)〕
= -60÷(+4x3)
= -60÷+12
= -5

記著口訣
正正得正，正負得負，負正得負，負負得正．　其實我剛剛上中學和剛剛學懂正負數　

2007-09-20 20:50:52 補充：
〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕 =〔(+8)-(+20)〕÷(+12)=(-12)÷(+12)=(-1)

〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕
=〔(+8)-(+20)〕÷(+12)
=(-12)÷(+12)
=(-1)

〔(+8)-(-4)(-5)〕÷〔(-4)(-3)〕
=(8-20) ÷ (12)
=-12/12
=-1

(+8+4-5)/(12)
7/12