Subtract 70/20 from 1/21, Solve 1/21

Subtract 70/20 from 1/21

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

1/21 - 70/20 is -145/42.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 21 × 20 = 420,
1/21 = 1 × 20/21 × 20 = 20/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
70/20 = 70 × 21/20 × 21 = 1470/420
Subtract the two like fractions:
20/420 - 1470/420 = 20 - 1470/420 = -1450/420
After reducing the fraction, the answer is -145/42

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