Answer:
6
Step-by-step explanation:
If the sum of the digits of a number is divisible by 9, then the number is divisible by 9.
So 6+7+8+5+Δ+4 = Δ + 30 has to be divisable by 9, and of course 0≤Δ≤9
36 is divisable by 9, so Δ has to be 6.
Answer: ?????
Step-by-step explanation: Are you finding who would have the most after a certain number of years have passed?