Answers

Subtract 63/7 from 81/20

1^st number: 4 1/20, 2^nd number: 9 0/7

81/20 - 63/7 is -99/20.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 20 and 7 is 140
   
   Next, find the equivalent fraction of both fractional numbers with denominator 140
2. For the 1st fraction, since 20 × 7 = 140,
   81/20 = 81 × 7/20 × 7 = 567/140
3. Likewise, for the 2nd fraction, since 7 × 20 = 140,
   63/7 = 63 × 20/7 × 20 = 1260/140
4. Subtract the two like fractions:
   567/140 - 1260/140 = 567 - 1260/140 = -693/140
5. After reducing the fraction, the answer is -99/20

MathStep (Works offline)

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

Related: ⁸¹/₄₀-⁶³/₇ ⁸¹/₂₀-⁶³/₁₄ ⁸¹/₆₀-⁶³/₇ ⁸¹/₂₀-⁶³/₂₁ ⁸¹/₂₀-⁶³/₃₅ ⁸¹/₂₀-⁶³/₄₉

Subtract Fractions Calculator