Subtract 7/9 from 18/21
18/21 - 7/9 is 5/63.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 9 is 63
Next, find the equivalent fraction of both fractional numbers with denominator 63 - For the 1st fraction, since 21 × 3 = 63,
18/21 = 18 × 3/21 × 3 = 54/63 - Likewise, for the 2nd fraction, since 9 × 7 = 63,
7/9 = 7 × 7/9 × 7 = 49/63 - Subtract the two like fractions:
54/63 - 49/63 = 54 - 49/63 = 5/63
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/21-7/9 18/21-14/9 18/42-7/9 18/21-7/18 54/21-7/9 18/21-21/9 18/63-7/9 18/21-7/27 90/21-7/9 18/21-35/9 18/21-7/45 18/21-49/9 18/21-7/63