Subtract 21/7 from 18/30
1st number: 18/30, 2nd number: 3 0/7
18/30 - 21/7 is -12/5.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 7 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 30 × 7 = 210,
18/30 = 18 × 7/30 × 7 = 126/210 - Likewise, for the 2nd fraction, since 7 × 30 = 210,
21/7 = 21 × 30/7 × 30 = 630/210 - Subtract the two like fractions:
126/210 - 630/210 = 126 - 630/210 = -504/210 - After reducing the fraction, the answer is -12/5
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/30-21/7 18/30-42/7 18/60-21/7 18/30-21/14 54/30-21/7 18/30-63/7 18/90-21/7 90/30-21/7 18/30-21/35 18/30-21/49