Subtract 42/21 from 1/18, Solve 1/18

Subtract 42/21 from 1/18

1^st number: 1/18, 2^nd number: 2 0/21

1/18 - 42/21 is -35/18.

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,
1/18 = 1 × 7/18 × 7 = 7/126
Likewise, for the 2nd fraction, since 21 × 6 = 126,
42/21 = 42 × 6/21 × 6 = 252/126
Subtract the two like fractions:
7/126 - 252/126 = 7 - 252/126 = -245/126
After reducing the fraction, the answer is -35/18

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