Subtract 3/20 from 18/42
18/42 - 3/20 is 39/140.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 42 × 10 = 420,
18/42 = 18 × 10/42 × 10 = 180/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
3/20 = 3 × 21/20 × 21 = 63/420 - Subtract the two like fractions:
180/420 - 63/420 = 180 - 63/420 = 117/420 - After reducing the fraction, the answer is 39/140
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/42-3/20 18/42-6/20 18/84-3/20 18/42-3/40 54/42-3/20 18/42-9/20 18/42-3/60 90/42-3/20 18/42-15/20 18/42-21/20