Subtract 21/18 from 8/21, Solve 8/21

Subtract 21/18 from 8/21

1^st number: 8/21, 2^nd number: 1 3/18

8/21 - 21/18 is -11/14.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 18 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 21 × 6 = 126,
8/21 = 8 × 6/21 × 6 = 48/126
Likewise, for the 2nd fraction, since 18 × 7 = 126,
21/18 = 21 × 7/18 × 7 = 147/126
Subtract the two like fractions:
48/126 - 147/126 = 48 - 147/126 = -99/126
After reducing the fraction, the answer is -11/14

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