Subtract 20/5 from 30/21
1st number: 1 9/21, 2nd number: 4 0/5
30/21 - 20/5 is -18/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 5 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 21 × 5 = 105,
30/21 = 30 × 5/21 × 5 = 150/105 - Likewise, for the 2nd fraction, since 5 × 21 = 105,
20/5 = 20 × 21/5 × 21 = 420/105 - Subtract the two like fractions:
150/105 - 420/105 = 150 - 420/105 = -270/105 - After reducing the fraction, the answer is -18/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 60/21-20/5 30/21-40/5 30/42-20/5 30/21-20/10 90/21-20/5 30/21-60/5 30/63-20/5 30/21-20/15 30/21-20/25 30/21-20/35