Subtract 20/16 from 72/21, Solve 3 9/21

Subtract 20/16 from 72/21

1^st number: 3 9/21, 2^nd number: 1 4/16

72/21 - 20/16 is 61/28.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 16 is 336

Next, find the equivalent fraction of both fractional numbers with denominator 336
For the 1st fraction, since 21 × 16 = 336,
72/21 = 72 × 16/21 × 16 = 1152/336
Likewise, for the 2nd fraction, since 16 × 21 = 336,
20/16 = 20 × 21/16 × 21 = 420/336
Subtract the two like fractions:
1152/336 - 420/336 = 1152 - 420/336 = 732/336
After reducing the fraction, the answer is 61/28
In mixed form: 25/28

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