Subtract 70/20 from 5/21, Solve 5/21

Subtract 70/20 from 5/21

1^st number: 5/21, 2^nd number: 3 10/20

5/21 - 70/20 is -137/42.

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,
5/21 = 5 × 20/21 × 20 = 100/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
70/20 = 70 × 21/20 × 21 = 1470/420
Subtract the two like fractions:
100/420 - 1470/420 = 100 - 1470/420 = -1370/420
After reducing the fraction, the answer is -137/42

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