Subtract 9/12 from 75/21, Solve 3 12/21

Subtract 9/12 from 75/21

1^st number: 3 12/21, 2^nd number: 9/12

75/21 - 9/12 is 79/28.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 12 is 84

Next, find the equivalent fraction of both fractional numbers with denominator 84
For the 1st fraction, since 21 × 4 = 84,
75/21 = 75 × 4/21 × 4 = 300/84
Likewise, for the 2nd fraction, since 12 × 7 = 84,
9/12 = 9 × 7/12 × 7 = 63/84
Subtract the two like fractions:
300/84 - 63/84 = 300 - 63/84 = 237/84
After reducing the fraction, the answer is 79/28
In mixed form: 223/28

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