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

Subtract 20/5 from 5/21

1^st number: 5/21, 2^nd number: 4 0/5

5/21 - 20/5 is -79/21.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 5 is 105

Next, find the equivalent fraction of both fractional numbers with denominator 105
For the 1st fraction, since 21 × 5 = 105,
5/21 = 5 × 5/21 × 5 = 25/105
Likewise, for the 2nd fraction, since 5 × 21 = 105,
20/5 = 20 × 21/5 × 21 = 420/105
Subtract the two like fractions:
25/105 - 420/105 = 25 - 420/105 = -395/105
After reducing the fraction, the answer is -79/21

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