Subtract 18/10 from 28/21
1st number: 1 7/21, 2nd number: 1 8/10
28/21 - 18/10 is -7/15.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 10 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 21 × 10 = 210,
28/21 = 28 × 10/21 × 10 = 280/210 - Likewise, for the 2nd fraction, since 10 × 21 = 210,
18/10 = 18 × 21/10 × 21 = 378/210 - Subtract the two like fractions:
280/210 - 378/210 = 280 - 378/210 = -98/210 - After reducing the fraction, the answer is -7/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 56/21-18/10 28/21-36/10 28/42-18/10 28/21-18/20 84/21-18/10 28/21-54/10 28/63-18/10 28/21-18/30 28/21-90/10 28/21-18/50 28/21-18/70