If two or more fractions have the same denominator, their sum is
obtained by adding the numerators.
WORK: 1 4 5 1 + 4 + 5 10 3
- + - + - = --------- = -- = 1-
7 7 7 7 7 7
If the fractions have different denominators, we must first express them
as equivalent fractions with the same denominator.