Subtract 21/40 from 15/81
15/81 - 21/40 is -367/1080.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 40 is 3240
Next, find the equivalent fraction of both fractional numbers with denominator 3240 - For the 1st fraction, since 81 × 40 = 3240,
15/81 = 15 × 40/81 × 40 = 600/3240 - Likewise, for the 2nd fraction, since 40 × 81 = 3240,
21/40 = 21 × 81/40 × 81 = 1701/3240 - Subtract the two like fractions:
600/3240 - 1701/3240 = 600 - 1701/3240 = -1101/3240 - After reducing the fraction, the answer is -367/1080
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/81-21/40 15/81-42/40 15/81-21/80 45/81-21/40 15/81-63/40 75/81-21/40