Subtract 15/40 from 8/42
8/42 - 15/40 is -31/168.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 42 × 20 = 840,
8/42 = 8 × 20/42 × 20 = 160/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
15/40 = 15 × 21/40 × 21 = 315/840 - Subtract the two like fractions:
160/840 - 315/840 = 160 - 315/840 = -155/840 - After reducing the fraction, the answer is -31/168
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/42-15/40 8/42-30/40 8/84-15/40 8/42-15/80 24/42-15/40 8/42-45/40 40/42-15/40 8/42-75/40 56/42-15/40