Subtract 3/21 from 42/54
42/54 - 3/21 is 40/63.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 54 and 21 is 378
Next, find the equivalent fraction of both fractional numbers with denominator 378 - For the 1st fraction, since 54 × 7 = 378,
42/54 = 42 × 7/54 × 7 = 294/378 - Likewise, for the 2nd fraction, since 21 × 18 = 378,
3/21 = 3 × 18/21 × 18 = 54/378 - Subtract the two like fractions:
294/378 - 54/378 = 294 - 54/378 = 240/378 - After reducing the fraction, the answer is 40/63
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/54-3/21 42/54-6/21 42/54-3/42 42/54-9/21 42/54-3/63 42/54-15/21