Subtract 4/70 from 72/21, Solve 3 9/21

Subtract 4/70 from 72/21

1^st number: 3 9/21, 2^nd number: 4/70

72/21 - 4/70 is 118/35.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 70 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 21 × 10 = 210,
72/21 = 72 × 10/21 × 10 = 720/210
Likewise, for the 2nd fraction, since 70 × 3 = 210,
4/70 = 4 × 3/70 × 3 = 12/210
Subtract the two like fractions:
720/210 - 12/210 = 720 - 12/210 = 708/210
After reducing the fraction, the answer is 118/35
In mixed form: 313/35

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