Subtract 18/12 from 21/45
1st number: 21/45, 2nd number: 1 6/12
21/45 - 18/12 is -31/30.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 12 is 180
Next, find the equivalent fraction of both fractional numbers with denominator 180 - For the 1st fraction, since 45 × 4 = 180,
21/45 = 21 × 4/45 × 4 = 84/180 - Likewise, for the 2nd fraction, since 12 × 15 = 180,
18/12 = 18 × 15/12 × 15 = 270/180 - Subtract the two like fractions:
84/180 - 270/180 = 84 - 270/180 = -186/180 - After reducing the fraction, the answer is -31/30
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/45-18/12 21/45-36/12 21/90-18/12 21/45-18/24 63/45-18/12 21/45-54/12 21/45-18/36 21/45-90/12 21/45-18/60 21/45-18/84