Subtract 21/7 from 7/81
1st number: 7/81, 2nd number: 3 0/7
7/81 - 21/7 is -236/81.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 7 is 567
Next, find the equivalent fraction of both fractional numbers with denominator 567 - For the 1st fraction, since 81 × 7 = 567,
7/81 = 7 × 7/81 × 7 = 49/567 - Likewise, for the 2nd fraction, since 7 × 81 = 567,
21/7 = 21 × 81/7 × 81 = 1701/567 - Subtract the two like fractions:
49/567 - 1701/567 = 49 - 1701/567 = -1652/567 - After reducing the fraction, the answer is -236/81
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/81-21/7 7/81-42/7 7/81-21/14 21/81-21/7 7/81-63/7 35/81-21/7 7/81-21/35 49/81-21/7 7/81-21/49