Subtract 18/54 from 72/21, Solve 3 9/21

Subtract 18/54 from 72/21

1^st number: 3 9/21, 2^nd number: 18/54

72/21 - 18/54 is 65/21.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 54 is 378

Next, find the equivalent fraction of both fractional numbers with denominator 378
For the 1st fraction, since 21 × 18 = 378,
72/21 = 72 × 18/21 × 18 = 1296/378
Likewise, for the 2nd fraction, since 54 × 7 = 378,
18/54 = 18 × 7/54 × 7 = 126/378
Subtract the two like fractions:
1296/378 - 126/378 = 1296 - 126/378 = 1170/378
After reducing the fraction, the answer is 65/21
In mixed form: 32/21

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