Subtract 72/7 from 21/40
1st number: 21/40, 2nd number: 10 2/7
21/40 - 72/7 is -2733/280.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 7 is 280
Next, find the equivalent fraction of both fractional numbers with denominator 280 - For the 1st fraction, since 40 × 7 = 280,
21/40 = 21 × 7/40 × 7 = 147/280 - Likewise, for the 2nd fraction, since 7 × 40 = 280,
72/7 = 72 × 40/7 × 40 = 2880/280 - Subtract the two like fractions:
147/280 - 2880/280 = 147 - 2880/280 = -2733/280
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/40-72/7 21/80-72/7 21/40-72/14 63/40-72/7 21/40-72/21 21/40-72/35 21/40-72/49