Subtract 9/21 from 90/80, Solve 1 10/80

Subtract 9/21 from 90/80

1^st number: 1 10/80, 2^nd number: 9/21

90/80 - 9/21 is 39/56.

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

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 80 × 21 = 1680,
90/80 = 90 × 21/80 × 21 = 1890/1680
Likewise, for the 2nd fraction, since 21 × 80 = 1680,
9/21 = 9 × 80/21 × 80 = 720/1680
Subtract the two like fractions:
1890/1680 - 720/1680 = 1890 - 720/1680 = 1170/1680
After reducing the fraction, the answer is 39/56

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