In order to add fractions you first need to make sure both fractions have the same denominator. If they don't have the same denominator like our example fraction doesn't, we need to convert them.
The least common denominator of 5 and 2 is 10 so we multiply both sides of the fraction 3/5 by its counterpart 2 and both sides of the fraction 1/2 by its counterpart 5. This gives us 6/10 + 5/10.
Notice counterpart does not always mean the denominator of the other fraction, it means the number that multiplied by the current denominator of your fraction will give you the least common denominator of both fractions.
Now we can easily add 6/10 + 5/10 to get 11/10.
(I copied my answer from my answer for another question that asked the same thing)
