Subtract 21/20 from 28/45
1st number: 28/45, 2nd number: 1 1/20
28/45 - 21/20 is -77/180.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 20 is 180
Next, find the equivalent fraction of both fractional numbers with denominator 180 - For the 1st fraction, since 45 × 4 = 180,
28/45 = 28 × 4/45 × 4 = 112/180 - Likewise, for the 2nd fraction, since 20 × 9 = 180,
21/20 = 21 × 9/20 × 9 = 189/180 - Subtract the two like fractions:
112/180 - 189/180 = 112 - 189/180 = -77/180
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 56/45-21/20 28/45-42/20 28/90-21/20 28/45-21/40 84/45-21/20 28/45-63/20 28/45-21/60