Answers

Subtract 10/21 from 18/42

18/42 - 10/21 is -1/21.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 42 and 21 is 42
   
   Next, find the equivalent fraction of both fractional numbers with denominator 42
2. For the 1st fraction, since 42 × 1 = 42,
   18/42 = 18 × 1/42 × 1 = 18/42
3. Likewise, for the 2nd fraction, since 21 × 2 = 42,
   10/21 = 10 × 2/21 × 2 = 20/42
4. Subtract the two like fractions:
   18/42 - 20/42 = 18 - 20/42 = -2/42
5. After reducing the fraction, the answer is -1/21

MathStep (Works offline)

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

Related: ³⁶/₄₂-¹⁰/₂₁ ¹⁸/₄₂-²⁰/₂₁ ¹⁸/₈₄-¹⁰/₂₁ ¹⁸/₄₂-¹⁰/₄₂ ⁵⁴/₄₂-¹⁰/₂₁ ¹⁸/₄₂-³⁰/₂₁ ¹⁸/₄₂-¹⁰/₆₃ ⁹⁰/₄₂-¹⁰/₂₁ ¹⁸/₄₂-⁵⁰/₂₁ ¹⁸/₄₂-⁷⁰/₂₁

Subtract Fractions Calculator