In general, to add or subtract fractions you need a common denominator. Here you have to mixed fractions and we can convert them to improper fractions to make the addition easier as well.
The rule to convert mixed fractions to improper fractions is:
a b/c= (ac+b)/c so in this case we have:
5/3 + 11/3 = 16/3 and you do the inverse to convert these improper fractions back to mixed fractions...
5 1/3
(I know that you could probably add them just by looking at them, but it is good practice to know how to do it properly for when the situation is not so simple...)