Subtract 42/12 from 30/70, Solve 30/70

Subtract 42/12 from 30/70

1^st number: 30/70, 2^nd number: 3 6/12

30/70 - 42/12 is -43/14.

Find the least common denominator or LCM of the two denominators:
LCM of 70 and 12 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 70 × 6 = 420,
30/70 = 30 × 6/70 × 6 = 180/420
Likewise, for the 2nd fraction, since 12 × 35 = 420,
42/12 = 42 × 35/12 × 35 = 1470/420
Subtract the two like fractions:
180/420 - 1470/420 = 180 - 1470/420 = -1290/420
After reducing the fraction, the answer is -43/14

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