Subtract 70/20 from 21/42, Solve 21/42

Subtract 70/20 from 21/42

1^st number: 21/42, 2^nd number: 3 10/20

21/42 - 70/20 is -3/1.

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,
21/42 = 21 × 10/42 × 10 = 210/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
70/20 = 70 × 21/20 × 21 = 1470/420
Subtract the two like fractions:
210/420 - 1470/420 = 210 - 1470/420 = -1260/420
After reducing the fraction, the answer is -3/1

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