Adding and subtracting fractions

Adding/ subracting fractions with common denominators

For two fractions \frac{a}{c} and \frac{b}{c} with a common denominator, their sum is defined as:

\frac{a}{c} + \frac{b}{c} = \frac{a + b}{c}

For example:

\frac{2}{8} + \frac{3}{8} = \frac{5}{8}

The same applies to subtraction:

\frac{a}{c} - \frac{b}{c} = \frac{a - b}{c}

Demonstration: \frac{4}{9} + \frac{1}{6} :

The lowest common denominator is the smallest number divisible by both of the denominators of the fractions without remainder.