Subtract 28/30 from 12/21
12/21 - 28/30 is -38/105.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 30 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 21 × 10 = 210,
12/21 = 12 × 10/21 × 10 = 120/210 - Likewise, for the 2nd fraction, since 30 × 7 = 210,
28/30 = 28 × 7/30 × 7 = 196/210 - Subtract the two like fractions:
120/210 - 196/210 = 120 - 196/210 = -76/210 - After reducing the fraction, the answer is -38/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/21-28/30 12/21-56/30 12/42-28/30 12/21-28/60 36/21-28/30 12/21-84/30 12/63-28/30 12/21-28/90 60/21-28/30 84/21-28/30