56 + (99 - 86) - 19 + (15 + 15) - 12= 56 + 13 - 19 + 30 - 12= 69 - 19 + 30 - 12= 50 + 30 - 12= 80 - 12= 68
Therefore, the answer is 68.
56 + (99 - 86) - 19 + (15 + 15) - 12
= 56 + 13 - 19 + 30 - 12
= 69 - 19 + 30 - 12
= 50 + 30 - 12
= 80 - 12
= 68
Therefore, the answer is 68.