Subtract 42/27 from 20/42, Solve 20/42

Subtract 42/27 from 20/42

1^st number: 20/42, 2^nd number: 1 15/27

20/42 - 42/27 is -68/63.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 27 is 378

Next, find the equivalent fraction of both fractional numbers with denominator 378
For the 1st fraction, since 42 × 9 = 378,
20/42 = 20 × 9/42 × 9 = 180/378
Likewise, for the 2nd fraction, since 27 × 14 = 378,
42/27 = 42 × 14/27 × 14 = 588/378
Subtract the two like fractions:
180/378 - 588/378 = 180 - 588/378 = -408/378
After reducing the fraction, the answer is -68/63

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