Subtract 21/30 from 20/90
20/90 - 21/30 is -43/90.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 30 is 90
Next, find the equivalent fraction of both fractional numbers with denominator 90 - For the 1st fraction, since 90 × 1 = 90,
20/90 = 20 × 1/90 × 1 = 20/90 - Likewise, for the 2nd fraction, since 30 × 3 = 90,
21/30 = 21 × 3/30 × 3 = 63/90 - Subtract the two like fractions:
20/90 - 63/90 = 20 - 63/90 = -43/90
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/90-21/30 20/90-42/30 20/90-21/60 60/90-21/30 20/90-63/30 20/90-21/90