Subtract 27/21 from 18/80, Solve 18/80

Subtract 27/21 from 18/80

1^st number: 18/80, 2^nd number: 1 6/21

18/80 - 27/21 is -297/280.

Find the least common denominator or LCM of the two denominators:
LCM of 80 and 21 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 80 × 21 = 1680,
18/80 = 18 × 21/80 × 21 = 378/1680
Likewise, for the 2nd fraction, since 21 × 80 = 1680,
27/21 = 27 × 80/21 × 80 = 2160/1680
Subtract the two like fractions:
378/1680 - 2160/1680 = 378 - 2160/1680 = -1782/1680
After reducing the fraction, the answer is -297/280

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