Subtract 15/8 from 81/42
1st number: 1 39/42, 2nd number: 1 7/8
81/42 - 15/8 is 3/56.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 8 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 42 × 4 = 168,
81/42 = 81 × 4/42 × 4 = 324/168 - Likewise, for the 2nd fraction, since 8 × 21 = 168,
15/8 = 15 × 21/8 × 21 = 315/168 - Subtract the two like fractions:
324/168 - 315/168 = 324 - 315/168 = 9/168 - After reducing the fraction, the answer is 3/56
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 81/42-30/8 81/84-15/8 81/42-15/16 81/42-45/8 81/42-15/24 81/42-75/8 81/42-15/40 81/42-15/56