Answers

Subtract 42/81 from 10/20

10/20 - 42/81 is -1/54.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 20 and 81 is 1620
   
   Next, find the equivalent fraction of both fractional numbers with denominator 1620
2. For the 1st fraction, since 20 × 81 = 1620,
   10/20 = 10 × 81/20 × 81 = 810/1620
3. Likewise, for the 2nd fraction, since 81 × 20 = 1620,
   42/81 = 42 × 20/81 × 20 = 840/1620
4. Subtract the two like fractions:
   810/1620 - 840/1620 = 810 - 840/1620 = -30/1620
5. After reducing the fraction, the answer is -1/54

MathStep (Works offline)

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

Related: ¹⁰/₂₀-⁸⁴/₈₁ ¹⁰/₄₀-⁴²/₈₁ ³⁰/₂₀-⁴²/₈₁ ¹⁰/₆₀-⁴²/₈₁ ⁵⁰/₂₀-⁴²/₈₁ ⁷⁰/₂₀-⁴²/₈₁

Subtract Fractions Calculator