Subtract 45/40 from 21/30
1st number: 21/30, 2nd number: 1 5/40
21/30 - 45/40 is -17/40.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 40 is 120
Next, find the equivalent fraction of both fractional numbers with denominator 120 - For the 1st fraction, since 30 × 4 = 120,
21/30 = 21 × 4/30 × 4 = 84/120 - Likewise, for the 2nd fraction, since 40 × 3 = 120,
45/40 = 45 × 3/40 × 3 = 135/120 - Subtract the two like fractions:
84/120 - 135/120 = 84 - 135/120 = -51/120 - After reducing the fraction, the answer is -17/40
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/30-45/40 21/30-90/40 21/60-45/40 21/30-45/80 63/30-45/40 21/90-45/40