Subtract 80/21 from 15/80, Solve 15/80

Subtract 80/21 from 15/80

1^st number: 15/80, 2^nd number: 3 17/21

15/80 - 80/21 is -1217/336.

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,
15/80 = 15 × 21/80 × 21 = 315/1680
Likewise, for the 2nd fraction, since 21 × 80 = 1680,
80/21 = 80 × 80/21 × 80 = 6400/1680
Subtract the two like fractions:
315/1680 - 6400/1680 = 315 - 6400/1680 = -6085/1680
After reducing the fraction, the answer is -1217/336

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