Subtract 81/8 from 30/21
1st number: 1 9/21, 2nd number: 10 1/8
30/21 - 81/8 is -487/56.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 8 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 21 × 8 = 168,
30/21 = 30 × 8/21 × 8 = 240/168 - Likewise, for the 2nd fraction, since 8 × 21 = 168,
81/8 = 81 × 21/8 × 21 = 1701/168 - Subtract the two like fractions:
240/168 - 1701/168 = 240 - 1701/168 = -1461/168 - After reducing the fraction, the answer is -487/56
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 60/21-81/8 30/42-81/8 30/21-81/16 90/21-81/8 30/63-81/8 30/21-81/24 30/21-81/40 30/21-81/56