Alright, so all we have to do here is solve the equation!
5 5/8 + m = 9
m = 9 - 5 5/8
Now is the tricky part - doing the subtraction! Let's change 9 to 8 8/8 (which is still equal to 9).
m = 8 8/8 - 5 5/8
Then we can subtract fairly easily!
m = (8 - 5) + (8/8 - 5/8)
m = 3 3/8 miles
Hope this helps!! :)