Subtract 20/21 from 45/54
45/54 - 20/21 is -5/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 54 and 21 is 378
Next, find the equivalent fraction of both fractional numbers with denominator 378 - For the 1st fraction, since 54 × 7 = 378,
45/54 = 45 × 7/54 × 7 = 315/378 - Likewise, for the 2nd fraction, since 21 × 18 = 378,
20/21 = 20 × 18/21 × 18 = 360/378 - Subtract the two like fractions:
315/378 - 360/378 = 315 - 360/378 = -45/378 - After reducing the fraction, the answer is -5/42
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