Subtract 30/21 from 3/18, Solve 3/18

Subtract 30/21 from 3/18

1^st number: 3/18, 2^nd number: 1 9/21

3/18 - 30/21 is -53/42.

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

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 18 × 7 = 126,
3/18 = 3 × 7/18 × 7 = 21/126
Likewise, for the 2nd fraction, since 21 × 6 = 126,
30/21 = 30 × 6/21 × 6 = 180/126
Subtract the two like fractions:
21/126 - 180/126 = 21 - 180/126 = -159/126
After reducing the fraction, the answer is -53/42

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