Subtract 20/54 from 42/21, Solve 2 0/21

Subtract 20/54 from 42/21

1^st number: 2 0/21, 2^nd number: 20/54

42/21 - 20/54 is 44/27.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 54 is 378

Next, find the equivalent fraction of both fractional numbers with denominator 378
For the 1st fraction, since 21 × 18 = 378,
42/21 = 42 × 18/21 × 18 = 756/378
Likewise, for the 2nd fraction, since 54 × 7 = 378,
20/54 = 20 × 7/54 × 7 = 140/378
Subtract the two like fractions:
756/378 - 140/378 = 756 - 140/378 = 616/378
After reducing the fraction, the answer is 44/27
In mixed form: 117/27

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