Subtract 21/42 from 6/20
6/20 - 21/42 is -1/5.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 20 and 42 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 20 × 21 = 420,
6/20 = 6 × 21/20 × 21 = 126/420 - Likewise, for the 2nd fraction, since 42 × 10 = 420,
21/42 = 21 × 10/42 × 10 = 210/420 - Subtract the two like fractions:
126/420 - 210/420 = 126 - 210/420 = -84/420 - After reducing the fraction, the answer is -1/5
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 12/20-21/42 6/40-21/42 6/20-21/84 18/20-21/42 6/20-63/42 6/60-21/42 30/20-21/42 42/20-21/42