Subtract 18/5 from 21/56, Solve 21/56

Subtract 18/5 from 21/56

1^st number: 21/56, 2^nd number: 3 3/5

21/56 - 18/5 is -129/40.

Find the least common denominator or LCM of the two denominators:
LCM of 56 and 5 is 280

Next, find the equivalent fraction of both fractional numbers with denominator 280
For the 1st fraction, since 56 × 5 = 280,
21/56 = 21 × 5/56 × 5 = 105/280
Likewise, for the 2nd fraction, since 5 × 56 = 280,
18/5 = 18 × 56/5 × 56 = 1008/280
Subtract the two like fractions:
105/280 - 1008/280 = 105 - 1008/280 = -903/280
After reducing the fraction, the answer is -129/40

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