Subtract 21/9 from 42/30
1st number: 1 12/30, 2nd number: 2 3/9
42/30 - 21/9 is -14/15.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 9 is 90
Next, find the equivalent fraction of both fractional numbers with denominator 90 - For the 1st fraction, since 30 × 3 = 90,
42/30 = 42 × 3/30 × 3 = 126/90 - Likewise, for the 2nd fraction, since 9 × 10 = 90,
21/9 = 21 × 10/9 × 10 = 210/90 - Subtract the two like fractions:
126/90 - 210/90 = 126 - 210/90 = -84/90 - After reducing the fraction, the answer is -14/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/30-21/9 42/30-42/9 42/60-21/9 42/30-21/18 42/30-63/9 42/90-21/9 42/30-21/27 42/30-21/45 42/30-21/63