Subtract 30/12 from 28/21
1st number: 1 7/21, 2nd number: 2 6/12
28/21 - 30/12 is -7/6.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 12 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 21 × 4 = 84,
28/21 = 28 × 4/21 × 4 = 112/84 - Likewise, for the 2nd fraction, since 12 × 7 = 84,
30/12 = 30 × 7/12 × 7 = 210/84 - Subtract the two like fractions:
112/84 - 210/84 = 112 - 210/84 = -98/84 - After reducing the fraction, the answer is -7/6
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 56/21-30/12 28/21-60/12 28/42-30/12 28/21-30/24 84/21-30/12 28/21-90/12 28/63-30/12 28/21-30/36 28/21-30/60 28/21-30/84