Subtract 18/42 from 8/40
8/40 - 18/42 is -8/35.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 42 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 40 × 21 = 840,
8/40 = 8 × 21/40 × 21 = 168/840 - Likewise, for the 2nd fraction, since 42 × 20 = 840,
18/42 = 18 × 20/42 × 20 = 360/840 - Subtract the two like fractions:
168/840 - 360/840 = 168 - 360/840 = -192/840 - After reducing the fraction, the answer is -8/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/40-18/42 8/40-36/42 8/80-18/42 8/40-18/84 24/40-18/42 8/40-54/42 8/40-90/42 56/40-18/42