Subtract 21/45 from 40/42
40/42 - 21/45 is 17/35.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 45 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 42 × 15 = 630,
40/42 = 40 × 15/42 × 15 = 600/630 - Likewise, for the 2nd fraction, since 45 × 14 = 630,
21/45 = 21 × 14/45 × 14 = 294/630 - Subtract the two like fractions:
600/630 - 294/630 = 600 - 294/630 = 306/630 - After reducing the fraction, the answer is 17/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 80/42-21/45 40/42-42/45 40/84-21/45 40/42-21/90 40/42-63/45