Subtract 80/4 from 42/21
1st number: 2 0/21, 2nd number: 20 0/4
42/21 - 80/4 is -18/1.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 4 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 21 × 4 = 84,
42/21 = 42 × 4/21 × 4 = 168/84 - Likewise, for the 2nd fraction, since 4 × 21 = 84,
80/4 = 80 × 21/4 × 21 = 1680/84 - Subtract the two like fractions:
168/84 - 1680/84 = 168 - 1680/84 = -1512/84 - After reducing the fraction, the answer is -18/1
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/21-80/4 42/21-80/8 42/63-80/4 42/21-80/12 42/21-80/20 42/21-80/28