Subtract 20/40 from 2/21
2/21 - 20/40 is -17/42.
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,
2/21 = 2 × 40/21 × 40 = 80/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
20/40 = 20 × 21/40 × 21 = 420/840 - Subtract the two like fractions:
80/840 - 420/840 = 80 - 420/840 = -340/840 - After reducing the fraction, the answer is -17/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 4/21-20/40 2/42-20/40 2/21-20/80 6/21-20/40 2/21-60/40 2/63-20/40 10/21-20/40 14/21-20/40