Subtract 18/21 from 6/8
6/8 - 18/21 is -3/28.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 8 and 21 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 8 × 21 = 168,
6/8 = 6 × 21/8 × 21 = 126/168 - Likewise, for the 2nd fraction, since 21 × 8 = 168,
18/21 = 18 × 8/21 × 8 = 144/168 - Subtract the two like fractions:
126/168 - 144/168 = 126 - 144/168 = -18/168 - After reducing the fraction, the answer is -3/28
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 12/8-18/21 6/8-36/21 6/16-18/21 6/8-18/42 18/8-18/21 6/8-54/21 6/24-18/21 6/8-18/63 30/8-18/21 6/8-90/21 6/40-18/21 42/8-18/21 6/56-18/21