You can look at this as two seprate parts. Rewrite this as 1 + 5/8. Next convert 1 to a fraction by putting it over 1. You can rewrite this as
1 5
--- + ---
1 8
Now we can add but we need to find a common denominator. In this case, 8 is the lowest common denominator so we can again rewrite this as
8 5
--- + ---
8 8
Then just add the fractions and you get
13/8