Subtract 21/20 from 18/21
1st number: 18/21, 2nd number: 1 1/20
18/21 - 21/20 is -27/140.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 21 × 20 = 420,
18/21 = 18 × 20/21 × 20 = 360/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
21/20 = 21 × 21/20 × 21 = 441/420 - Subtract the two like fractions:
360/420 - 441/420 = 360 - 441/420 = -81/420 - After reducing the fraction, the answer is -27/140
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