Subtract 21/42 from 8/30
8/30 - 21/42 is -7/30.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 42 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 30 × 7 = 210,
8/30 = 8 × 7/30 × 7 = 56/210 - Likewise, for the 2nd fraction, since 42 × 5 = 210,
21/42 = 21 × 5/42 × 5 = 105/210 - Subtract the two like fractions:
56/210 - 105/210 = 56 - 105/210 = -49/210 - After reducing the fraction, the answer is -7/30
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/30-21/42 8/60-21/42 8/30-21/84 24/30-21/42 8/30-63/42 8/90-21/42 40/30-21/42 56/30-21/42