When we add two fractions, they must have the same denominator.
We use equivalent fractions to change them into two fractions with the same lowest common denominator.
Example
Work out
| 3 | + | 1 |
| 10 | 15 |
Answer
We must first find the lowest common multiple of 10 and 15, which is 30.
Then we change each fraction into 30ths.
30 ÷ 10 = 3 so we multiply top and bottom of the first fraction by 3.
30 ÷ 15 = 2 so we multiply top and bottom of the second fraction by 2.
| 3 | + | 1 |
| 10 | 15 |
| = | 3 × 3 | + | 1 × 2 |
| 10 × 3 | 15 × 2 |
| = | 9 | + | 2 |
| 30 | 30 |
| = | 11 |
| 30 |
We must always simplify or reduce our answer to its lowest possible terms.
This activity contains 10 questions
