Subtract 42/81 from 9/21
9/21 - 42/81 is -17/189.
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,
9/21 = 9 × 27/21 × 27 = 243/567 - Likewise, for the 2nd fraction, since 81 × 7 = 567,
42/81 = 42 × 7/81 × 7 = 294/567 - Subtract the two like fractions:
243/567 - 294/567 = 243 - 294/567 = -51/567 - After reducing the fraction, the answer is -17/189
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