Subtract 15/21 from 7/42
7/42 - 15/21 is -23/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 21 is 42
Next, find the equivalent fraction of both fractional numbers with denominator 42 - For the 1st fraction, since 42 × 1 = 42,
7/42 = 7 × 1/42 × 1 = 7/42 - Likewise, for the 2nd fraction, since 21 × 2 = 42,
15/21 = 15 × 2/21 × 2 = 30/42 - Subtract the two like fractions:
7/42 - 30/42 = 7 - 30/42 = -23/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/42-15/21 7/42-30/21 7/84-15/21 7/42-15/42 21/42-15/21 7/42-45/21 7/42-15/63 35/42-15/21 7/42-75/21 49/42-15/21