Subtract 15/40 from 27/21, Solve 1 6/21

Subtract 15/40 from 27/21

1^st number: 1 6/21, 2^nd number: 15/40

27/21 - 15/40 is 51/56.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 21 × 40 = 840,
27/21 = 27 × 40/21 × 40 = 1080/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
15/40 = 15 × 21/40 × 21 = 315/840
Subtract the two like fractions:
1080/840 - 315/840 = 1080 - 315/840 = 765/840
After reducing the fraction, the answer is 51/56

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