Subtract 56/15 from 1/21, Solve 1/21

Subtract 56/15 from 1/21

1^st number: 1/21, 2^nd number: 3 11/15

1/21 - 56/15 is -129/35.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 15 is 105

Next, find the equivalent fraction of both fractional numbers with denominator 105
For the 1st fraction, since 21 × 5 = 105,
1/21 = 1 × 5/21 × 5 = 5/105
Likewise, for the 2nd fraction, since 15 × 7 = 105,
56/15 = 56 × 7/15 × 7 = 392/105
Subtract the two like fractions:
5/105 - 392/105 = 5 - 392/105 = -387/105
After reducing the fraction, the answer is -129/35

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