Question

-28:[(-12+9)-(9-12:3)+1] resultado

Answer 1

-28 : [( - 12 + 9) - (9 - 12 :3)+1
-28 : (-3 - (-1) +1)
- 28 : -3 + 1
-30
esperó q te sirva saludos :)

Answer 2

-28:[(-12+9)-(9-12:3)+1] =     -28:[(-12+9)-(9-4) +1]

                                       =     -28:[-12+9-9+4+1]

                                      =      -28:[-7]

                                      =      +4