Subtract 28/21 from 12/18
1st number: 12/18, 2nd number: 1 7/21
12/18 - 28/21 is -2/3.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 18 and 21 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 18 × 7 = 126,
12/18 = 12 × 7/18 × 7 = 84/126 - Likewise, for the 2nd fraction, since 21 × 6 = 126,
28/21 = 28 × 6/21 × 6 = 168/126 - Subtract the two like fractions:
84/126 - 168/126 = 84 - 168/126 = -84/126 - After reducing the fraction, the answer is -2/3
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/18-28/21 12/18-56/21 12/36-28/21 12/18-28/42 36/18-28/21 12/18-84/21 12/54-28/21 12/18-28/63 60/18-28/21 12/90-28/21 84/18-28/21