Answer: 108
Firstly we can divide 800, by 8. We get 100 (because 8:8 is 1, and we’ve to just copy zeros).
800 : 8 = 100
Secondly, we just add to score of previous operation, to rest of the quotient (rest is 864 - 800 = 64, because we did operation with 800):
100 + 64 : 8 =
100 + 8 =
108
Then the answer is 108.