數學問題(1)

1) = -18000/-900
= +20

2) = +8640/+8640
= +1

3) = +7X(-2/7)X(-3/2)
= -2x(-3/2)
= +3

4) = (-1/2)x(+1/2)x(-4)
= (-1/4)X(-4)
= +1

5) = +21+(+20)-(+30)
= +41-30
= +11

6) = -8-(-6)-(-20)
= -8+6+20
= +18

7) = [+8-(-12)] / [-2]
= [+8+12] / [-2]
= [+20] / [-2]
= -10

8) = [-15+(-15)] / [12]
= [-15-15] / [12]
= [-30] / [12]
= -2又1/2 or -2.5

9) = [-13-2] / [+2+1]
= [-15] / [+3]
= -5

10) = [-20] / [-2+1]
= [-20] / -1
= +20

* 負負得正
正負得負
正正得正