Subtract 20/21 from 4/45
4/45 - 20/21 is -272/315.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 21 is 315
Next, find the equivalent fraction of both fractional numbers with denominator 315 - For the 1st fraction, since 45 × 7 = 315,
4/45 = 4 × 7/45 × 7 = 28/315 - Likewise, for the 2nd fraction, since 21 × 15 = 315,
20/21 = 20 × 15/21 × 15 = 300/315 - Subtract the two like fractions:
28/315 - 300/315 = 28 - 300/315 = -272/315
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 8/45-20/21 4/45-40/21 4/90-20/21 4/45-20/42 12/45-20/21 4/45-60/21 4/45-20/63 20/45-20/21 28/45-20/21