Subtract 30/9 from 81/42, Solve 1 39/42

Subtract 30/9 from 81/42

1^st number: 1 39/42, 2^nd number: 3 3/9

81/42 - 30/9 is -59/42.

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,
81/42 = 81 × 3/42 × 3 = 243/126
Likewise, for the 2nd fraction, since 9 × 14 = 126,
30/9 = 30 × 14/9 × 14 = 420/126
Subtract the two like fractions:
243/126 - 420/126 = 243 - 420/126 = -177/126
After reducing the fraction, the answer is -59/42

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