Subtract 21/80 from 28/81
28/81 - 21/80 is 539/6480.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 80 is 6480
Next, find the equivalent fraction of both fractional numbers with denominator 6480 - For the 1st fraction, since 81 × 80 = 6480,
28/81 = 28 × 80/81 × 80 = 2240/6480 - Likewise, for the 2nd fraction, since 80 × 81 = 6480,
21/80 = 21 × 81/80 × 81 = 1701/6480 - Subtract the two like fractions:
2240/6480 - 1701/6480 = 2240 - 1701/6480 = 539/6480
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 56/81-21/80 28/81-42/80 84/81-21/80 28/81-63/80