Subtract 72/9 from 30/42, Solve 30/42

Subtract 72/9 from 30/42

1^st number: 30/42, 2^nd number: 8 0/9

30/42 - 72/9 is -51/7.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 9 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 42 × 3 = 126,
30/42 = 30 × 3/42 × 3 = 90/126
Likewise, for the 2nd fraction, since 9 × 14 = 126,
72/9 = 72 × 14/9 × 14 = 1008/126
Subtract the two like fractions:
90/126 - 1008/126 = 90 - 1008/126 = -918/126
After reducing the fraction, the answer is -51/7

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