How do you add three fractions without the same denominators?
When you want to add fractions that have different denominators,
you have to convert them into fractions that do have the same
denominators. So for example, how much is a half plus a third? Both
of these can be converted into sixths, so one half equals three
sixths, and one third equals two sixths. Three sixths plus two
sixths equals five sixths. That's the answer. If you have three
fractions with different denominators, the procedure is the same.
Convert all three into fractions with the same denominators, then
add them.