Subtract 90/40 from 15/21
1st number: 15/21, 2nd number: 2 10/40
15/21 - 90/40 is -43/28.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 21 × 40 = 840,
15/21 = 15 × 40/21 × 40 = 600/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
90/40 = 90 × 21/40 × 21 = 1890/840 - Subtract the two like fractions:
600/840 - 1890/840 = 600 - 1890/840 = -1290/840 - After reducing the fraction, the answer is -43/28
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/21-90/40 15/42-90/40 15/21-90/80 45/21-90/40 15/63-90/40 75/21-90/40