Answers

Subtract 9/18 from 9/21

9/21 - 9/18 is -1/14.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 18 is 126
   
   Next, find the equivalent fraction of both fractional numbers with denominator 126
2. For the 1st fraction, since 21 × 6 = 126,
   9/21 = 9 × 6/21 × 6 = 54/126
3. Likewise, for the 2nd fraction, since 18 × 7 = 126,
   9/18 = 9 × 7/18 × 7 = 63/126
4. Subtract the two like fractions:
   54/126 - 63/126 = 54 - 63/126 = -9/126
5. After reducing the fraction, the answer is -1/14

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad

Related: ¹⁸/₂₁-⁹/₁₈ ⁹/₄₂-⁹/₁₈ ⁹/₂₁-⁹/₃₆ ²⁷/₂₁-⁹/₁₈ ⁹/₂₁-²⁷/₁₈ ⁹/₆₃-⁹/₁₈ ⁹/₂₁-⁹/₅₄ ⁴⁵/₂₁-⁹/₁₈ ⁹/₂₁-⁴⁵/₁₈ ⁹/₂₁-⁹/₉₀ ⁶³/₂₁-⁹/₁₈ ⁹/₂₁-⁶³/₁₈

Subtract Fractions Calculator