Subtract 18/21 from 6/90
6/90 - 18/21 is -83/105.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
6/90 = 6 × 7/90 × 7 = 42/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
18/21 = 18 × 30/21 × 30 = 540/630 - Subtract the two like fractions:
42/630 - 540/630 = 42 - 540/630 = -498/630 - After reducing the fraction, the answer is -83/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 12/90-18/21 6/90-36/21 6/90-18/42 18/90-18/21 6/90-54/21 6/90-18/63 30/90-18/21 6/90-90/21 42/90-18/21