Adding and subtracting fractions
Watch this video to learn about adding and subtracting fractions.
It is easy to add fractions when the numbers on the bottom are the same.
All you need to do is add the tops of the fractions together.
So \(\frac{2}{9} + \frac{5}{9} = \frac{7}{9}\)
Sometimes you need to cancel down the answer to its simplest terms.
\(\frac{3}{{10}} + \frac{1}{{10}} = \frac{4}{{10}} = \frac{2}{5}\)
When the numbers on the bottom are not the same to start with, you use equivalent fractions to make them the same.
Question
\(\frac{3}{5} + \frac{1}{4}\)
The numbers on the bottom of the fractions are not the same.
You can use equivalent fractions to make them both equal to \(20\).
\(\frac{3}{5} = \frac{{12}}{{20}}\) and \(\frac{1}{4} = \frac{5}{{20}}\).
Now you can add them together.
\(\frac{{12}}{{20}} + \frac{5}{{20}} = \frac{{17}}{{20}}\)
Subtraction
You subtract using the same methods you use for adding.
Question
Calculate \(\frac{3}{5} - \frac{1}{5}\)
\(\frac{3}{5} - \frac{1}{5} = \frac{2}{5}\)
Question
Calculate \(\frac{5}{8} - \frac{3}{{10}}\)
\(8\) and \(10\) both divide into \(40\). So re-write the fractions using \(40\) as the number on the bottom of each one.
\(\frac{5}{8} - \frac{3}{{10}} = \frac{{25}}{{40}} - \frac{{12}}{{40}} = \frac{{13}}{{40}}\)
