Subtract 21/30 from 21/72
21/72 - 21/30 is -49/120.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 72 and 30 is 360
Next, find the equivalent fraction of both fractional numbers with denominator 360 - For the 1st fraction, since 72 × 5 = 360,
21/72 = 21 × 5/72 × 5 = 105/360 - Likewise, for the 2nd fraction, since 30 × 12 = 360,
21/30 = 21 × 12/30 × 12 = 252/360 - Subtract the two like fractions:
105/360 - 252/360 = 105 - 252/360 = -147/360 - After reducing the fraction, the answer is -49/120
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/72-21/30 21/72-42/30 21/72-21/60 63/72-21/30 21/72-63/30 21/72-21/90