Subtract 18/35 from 21/42
21/42 - 18/35 is -1/70.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 35 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 42 × 5 = 210,
21/42 = 21 × 5/42 × 5 = 105/210 - Likewise, for the 2nd fraction, since 35 × 6 = 210,
18/35 = 18 × 6/35 × 6 = 108/210 - Subtract the two like fractions:
105/210 - 108/210 = 105 - 108/210 = -3/210 - After reducing the fraction, the answer is -1/70
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 21/42-36/35 21/84-18/35 21/42-18/70 63/42-18/35 21/42-54/35 21/42-90/35