Subtract 21/81 from 42/90
42/90 - 21/81 is 28/135.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 81 is 810
Next, find the equivalent fraction of both fractional numbers with denominator 810 - For the 1st fraction, since 90 × 9 = 810,
42/90 = 42 × 9/90 × 9 = 378/810 - Likewise, for the 2nd fraction, since 81 × 10 = 810,
21/81 = 21 × 10/81 × 10 = 210/810 - Subtract the two like fractions:
378/810 - 210/810 = 378 - 210/810 = 168/810 - After reducing the fraction, the answer is 28/135
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