Subtract 28/54 from 1/21, Solve 1/21

Subtract 28/54 from 1/21

1/21 - 28/54 is -89/189.

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,
1/21 = 1 × 18/21 × 18 = 18/378
Likewise, for the 2nd fraction, since 54 × 7 = 378,
28/54 = 28 × 7/54 × 7 = 196/378
Subtract the two like fractions:
18/378 - 196/378 = 18 - 196/378 = -178/378
After reducing the fraction, the answer is -89/189

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