Subtract 81/56 from 40/21, Solve 1 19/21

Subtract 81/56 from 40/21

1^st number: 1 19/21, 2^nd number: 1 25/56

40/21 - 81/56 is 11/24.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 56 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 21 × 8 = 168,
40/21 = 40 × 8/21 × 8 = 320/168
Likewise, for the 2nd fraction, since 56 × 3 = 168,
81/56 = 81 × 3/56 × 3 = 243/168
Subtract the two like fractions:
320/168 - 243/168 = 320 - 243/168 = 77/168
After reducing the fraction, the answer is 11/24

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