Subtract 72/20 from 3/42, Solve 3/42

Subtract 72/20 from 3/42

1^st number: 3/42, 2^nd number: 3 12/20

3/42 - 72/20 is -247/70.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 42 × 10 = 420,
3/42 = 3 × 10/42 × 10 = 30/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
72/20 = 72 × 21/20 × 21 = 1512/420
Subtract the two like fractions:
30/420 - 1512/420 = 30 - 1512/420 = -1482/420
After reducing the fraction, the answer is -247/70

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