To add fractions with the same denominator you have to add the numerators and leave the same denominator.
Step-by-step explanation:
To add fractions with different denominators, the first thing that you have to do is find a common denominator: this is the least common multiple of the denominators that you have.
Then we multiply each numerator by the number that we have multiplied the denominator by.
Finally, we add the numerators that we have obtained and keep the same denominator.