Subtract 2/40 from 18/21
18/21 - 2/40 is 113/140.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 21 × 40 = 840,
18/21 = 18 × 40/21 × 40 = 720/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
2/40 = 2 × 21/40 × 21 = 42/840 - Subtract the two like fractions:
720/840 - 42/840 = 720 - 42/840 = 678/840 - After reducing the fraction, the answer is 113/140
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/21-2/40 18/21-4/40 18/42-2/40 18/21-2/80 54/21-2/40 18/21-6/40 18/63-2/40 90/21-2/40 18/21-10/40 18/21-14/40