Subtract 30/90 from 21/12
1st number: 1 9/12, 2nd number: 30/90
21/12 - 30/90 is 17/12.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 12 and 90 is 180
Next, find the equivalent fraction of both fractional numbers with denominator 180 - For the 1st fraction, since 12 × 15 = 180,
21/12 = 21 × 15/12 × 15 = 315/180 - Likewise, for the 2nd fraction, since 90 × 2 = 180,
30/90 = 30 × 2/90 × 2 = 60/180 - Subtract the two like fractions:
315/180 - 60/180 = 315 - 60/180 = 255/180 - After reducing the fraction, the answer is 17/12
- In mixed form: 15/12
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/12-30/90 21/12-60/90 21/24-30/90 63/12-30/90 21/36-30/90 21/60-30/90 21/84-30/90