Subtract 10/20 from 9/21
9/21 - 10/20 is -1/14.
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,
9/21 = 9 × 20/21 × 20 = 180/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
10/20 = 10 × 21/20 × 21 = 210/420 - Subtract the two like fractions:
180/420 - 210/420 = 180 - 210/420 = -30/420 - After reducing the fraction, the answer is -1/14
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