Subtract 21/84 from 18/90
18/90 - 21/84 is -1/20.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 84 is 1260
Next, find the equivalent fraction of both fractional numbers with denominator 1260 - For the 1st fraction, since 90 × 14 = 1260,
18/90 = 18 × 14/90 × 14 = 252/1260 - Likewise, for the 2nd fraction, since 84 × 15 = 1260,
21/84 = 21 × 15/84 × 15 = 315/1260 - Subtract the two like fractions:
252/1260 - 315/1260 = 252 - 315/1260 = -63/1260 - After reducing the fraction, the answer is -1/20
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/90-21/84 18/90-42/84 54/90-21/84 18/90-63/84