Subtract 42/54 from 4/21, Solve 4/21

Subtract 42/54 from 4/21

4/21 - 42/54 is -37/63.

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,
4/21 = 4 × 18/21 × 18 = 72/378
Likewise, for the 2nd fraction, since 54 × 7 = 378,
42/54 = 42 × 7/54 × 7 = 294/378
Subtract the two like fractions:
72/378 - 294/378 = 72 - 294/378 = -222/378
After reducing the fraction, the answer is -37/63

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