Answer:
He drives an extra 4/10 of a mile every day.
Step-by-step explanation:
Looking at our pattern, we see that to get from 84 2/10 to 84 6/10, we would add 4/10.
Similarly, to get from 84 6/10 to 85, we would add 4/10.
This means we add 4/10 of a mile every day.
To check, we can subtract:
85-84 6/10 = 4/10
84 6/10-84 2/10 = 4/10