Subtract 42/21 from 3/40
1st number: 3/40, 2nd number: 2 0/21
3/40 - 42/21 is -77/40.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 21 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 40 × 21 = 840,
3/40 = 3 × 21/40 × 21 = 63/840 - Likewise, for the 2nd fraction, since 21 × 40 = 840,
42/21 = 42 × 40/21 × 40 = 1680/840 - Subtract the two like fractions:
63/840 - 1680/840 = 63 - 1680/840 = -1617/840 - After reducing the fraction, the answer is -77/40
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 6/40-42/21 3/40-84/21 3/80-42/21 9/40-42/21 3/40-42/63 15/40-42/21 21/40-42/21