Addition and Subtraction:
Denominators of fractions being added or subtracted must be the similar.
The resulting sum or difference is then the sum/difference of the numerators of the fractions being added or subtracted.
Examples:
2/3 + 1/3 = 2+1/3 = 1
4/7 + 1/7 = 4+1/7 = 5/7
4/9 -2/9 = 4-2/9 = 2/9
8/11 - 2/11 - 5/11 = 8-2-5/11 = 1/11