Subtract 21/72 from 8/90
8/90 - 21/72 is -73/360.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 72 is 360
Next, find the equivalent fraction of both fractional numbers with denominator 360 - For the 1st fraction, since 90 × 4 = 360,
8/90 = 8 × 4/90 × 4 = 32/360 - Likewise, for the 2nd fraction, since 72 × 5 = 360,
21/72 = 21 × 5/72 × 5 = 105/360 - Subtract the two like fractions:
32/360 - 105/360 = 32 - 105/360 = -73/360
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/90-21/72 8/90-42/72 24/90-21/72 8/90-63/72 40/90-21/72 56/90-21/72