Subtract 18/81 from 20/21
20/21 - 18/81 is 46/63.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 81 is 567
Next, find the equivalent fraction of both fractional numbers with denominator 567 - For the 1st fraction, since 21 × 27 = 567,
20/21 = 20 × 27/21 × 27 = 540/567 - Likewise, for the 2nd fraction, since 81 × 7 = 567,
18/81 = 18 × 7/81 × 7 = 126/567 - Subtract the two like fractions:
540/567 - 126/567 = 540 - 126/567 = 414/567 - After reducing the fraction, the answer is 46/63
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