Phá ngoặc theo quy tắc: 1) -(5-9+8-3) 2) +(3-5+7-9) 3) -(-9+15-4+7) 4) +(-12-14+13-9) 5) -(-5+7-3+9)

`1, - (5 - 9 + 8 - 3)`

`= -5 + 9 - 8 + 3`

`= 4 - 5`

`= - 1`

________________________

`2, + (3 - 5 + 7 - 9)`

`= 3 - 5 + 7 - 9`

`= -2 - 2`

`= -4`

________________________

`3, - (-9 + 15 - 4 + 7)`

`= 9 - 15 + 4 - 7`

`= -6 - 3`

`= -9`

_________________________

`4, + (-12 - 14 + 13 - 9)`

`= -12 - 14 + 13 - 9`

`= -26 + 4`

`= -22`

__________________________

`5, - (-5 + 7 - 3 + 9)`

`= 5 - 7 + 3 - 9`

`= -2 - 6`

`= -8`

`text{#maingoctranthi}`