Subtract 2/90 from 21/80
21/80 - 2/90 is 173/720.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 80 and 90 is 720
Next, find the equivalent fraction of both fractional numbers with denominator 720 - For the 1st fraction, since 80 × 9 = 720,
21/80 = 21 × 9/80 × 9 = 189/720 - Likewise, for the 2nd fraction, since 90 × 8 = 720,
2/90 = 2 × 8/90 × 8 = 16/720 - Subtract the two like fractions:
189/720 - 16/720 = 189 - 16/720 = 173/720
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/80-2/90 21/80-4/90 63/80-2/90 21/80-6/90 21/80-10/90 21/80-14/90