Subtract 1/20 from 21/45
21/45 - 1/20 is 5/12.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 20 is 180
Next, find the equivalent fraction of both fractional numbers with denominator 180 - For the 1st fraction, since 45 × 4 = 180,
21/45 = 21 × 4/45 × 4 = 84/180 - Likewise, for the 2nd fraction, since 20 × 9 = 180,
1/20 = 1 × 9/20 × 9 = 9/180 - Subtract the two like fractions:
84/180 - 9/180 = 84 - 9/180 = 75/180 - After reducing the fraction, the answer is 5/12
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/45-1/20 21/45-2/20 21/90-1/20 21/45-1/40 63/45-1/20 21/45-3/20 21/45-1/60 21/45-5/20 21/45-7/20