Subtract 40/8 from 21/84
1st number: 21/84, 2nd number: 5 0/8
21/84 - 40/8 is -19/4.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 84 and 8 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 84 × 2 = 168,
21/84 = 21 × 2/84 × 2 = 42/168 - Likewise, for the 2nd fraction, since 8 × 21 = 168,
40/8 = 40 × 21/8 × 21 = 840/168 - Subtract the two like fractions:
42/168 - 840/168 = 42 - 840/168 = -798/168 - After reducing the fraction, the answer is -19/4
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/84-40/8 21/84-80/8 21/84-40/16 63/84-40/8 21/84-40/24 21/84-40/56