Fraction Subtraction with Like Denominators
When two fractions have the same denominator, subtraction is straightforward: subtract the numerators and keep the denominator the same.
Method
- Check the denominators. If they match, you can subtract directly.
- Subtract the top numbers.
- Example idea: (\frac{a}{b} - \frac{c}{b} = \frac{a-c}{b})
- Keep the denominator unchanged.
- Simplify the result if possible.
- Reduce the fraction by dividing numerator and denominator by their greatest common factor.
- If the answer is an improper fraction, you may also convert it to a mixed number if that is the expected form.
Example
(\frac{7}{9} - \frac{2}{9} = \frac{5}{9})
Check your work
- Make sure you subtracted only the numerators.
- Confirm the denominator stayed the same.
- See whether the fraction can be reduced.
Helpful reminder
If the numerator of the second fraction is larger than the first, the answer will be negative. You still subtract the numerators carefully and keep the denominator the same.