Subtract 21/81 from 15/30
15/30 - 21/81 is 13/54.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 81 is 810
Next, find the equivalent fraction of both fractional numbers with denominator 810 - For the 1st fraction, since 30 × 27 = 810,
15/30 = 15 × 27/30 × 27 = 405/810 - Likewise, for the 2nd fraction, since 81 × 10 = 810,
21/81 = 21 × 10/81 × 10 = 210/810 - Subtract the two like fractions:
405/810 - 210/810 = 405 - 210/810 = 195/810 - After reducing the fraction, the answer is 13/54
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