Subtract 80/81 from 21/84
21/84 - 80/81 is -239/324.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 84 and 81 is 2268
Next, find the equivalent fraction of both fractional numbers with denominator 2268 - For the 1st fraction, since 84 × 27 = 2268,
21/84 = 21 × 27/84 × 27 = 567/2268 - Likewise, for the 2nd fraction, since 81 × 28 = 2268,
80/81 = 80 × 28/81 × 28 = 2240/2268 - Subtract the two like fractions:
567/2268 - 2240/2268 = 567 - 2240/2268 = -1673/2268 - After reducing the fraction, the answer is -239/324
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/84-80/81 63/84-80/81