- 12 + ( - 21 + 13 ) - 17 + 48 = 11
= - 12 - 8 - 17 + 48 =
= - 20 - 17 + 48 =
= - 37 + 48 =
= 11
__________________
- 12 + [ ( - 21 + 13 ) - 17 + 48 ] = 11
= - 12 + ( - 8 - 17 + 48 ) =
= - 12 + ( - 25 + 48 ) =
= - 12 + 23 =
= 11
________________________
- 12 + ( - 21 + 13 ) - ( 17 + 48 ) = - 85
= - 12 - 8 - 65 =
= - 20 - 65 =
= - 85
