Subtract 72/20 from 5/21, Solve 5/21

Subtract 72/20 from 5/21

1^st number: 5/21, 2^nd number: 3 12/20

5/21 - 72/20 is -353/105.

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,
72/20 = 72 × 21/20 × 21 = 1512/420
Subtract the two like fractions:
100/420 - 1512/420 = 100 - 1512/420 = -1412/420
After reducing the fraction, the answer is -353/105

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