Subtract 7/15 from 21/81
21/81 - 7/15 is -28/135.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 15 is 405
Next, find the equivalent fraction of both fractional numbers with denominator 405 - For the 1st fraction, since 81 × 5 = 405,
21/81 = 21 × 5/81 × 5 = 105/405 - Likewise, for the 2nd fraction, since 15 × 27 = 405,
7/15 = 7 × 27/15 × 27 = 189/405 - Subtract the two like fractions:
105/405 - 189/405 = 105 - 189/405 = -84/405 - After reducing the fraction, the answer is -28/135
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