Subtract 21/81 from 5/7
5/7 - 21/81 is 86/189.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 7 and 81 is 567
Next, find the equivalent fraction of both fractional numbers with denominator 567 - For the 1st fraction, since 7 × 81 = 567,
5/7 = 5 × 81/7 × 81 = 405/567 - Likewise, for the 2nd fraction, since 81 × 7 = 567,
21/81 = 21 × 7/81 × 7 = 147/567 - Subtract the two like fractions:
405/567 - 147/567 = 405 - 147/567 = 258/567 - After reducing the fraction, the answer is 86/189
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 10/7-21/81 5/7-42/81 5/14-21/81 15/7-21/81 5/7-63/81 5/21-21/81 25/7-21/81 5/35-21/81 35/7-21/81 5/49-21/81