I think it's 81 but i can't be sure...
78
12 - 78 + 2397543 - 124 + 3 = 2397356
The answer is 97.
78+78-:(85)/(78)+7,879=1405
78 + 89 + 167 + 897 + 78 = 1309
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 = 78
55 + 82 + 92 + 78 + 100 + 96 + 78 = 581
78 + 78 = 156
3.14 + 2.18+ 1.78 = 7.10
78 minus78
84+73+78 = 235.
69 + 78 + 82 = 229