Subtract 21/80 from 70/21, Solve 3 7/21

Subtract 21/80 from 70/21

1^st number: 3 7/21, 2^nd number: 21/80

70/21 - 21/80 is 737/240.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 80 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 21 × 80 = 1680,
70/21 = 70 × 80/21 × 80 = 5600/1680
Likewise, for the 2nd fraction, since 80 × 21 = 1680,
21/80 = 21 × 21/80 × 21 = 441/1680
Subtract the two like fractions:
5600/1680 - 441/1680 = 5600 - 441/1680 = 5159/1680
After reducing the fraction, the answer is 737/240
In mixed form: 317/240

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