Subtract 21/9 from 18/80, Solve 18/80

Subtract 21/9 from 18/80

1^st number: 18/80, 2^nd number: 2 3/9

18/80 - 21/9 is -253/120.

Find the least common denominator or LCM of the two denominators:
LCM of 80 and 9 is 720

Next, find the equivalent fraction of both fractional numbers with denominator 720
For the 1st fraction, since 80 × 9 = 720,
18/80 = 18 × 9/80 × 9 = 162/720
Likewise, for the 2nd fraction, since 9 × 80 = 720,
21/9 = 21 × 80/9 × 80 = 1680/720
Subtract the two like fractions:
162/720 - 1680/720 = 162 - 1680/720 = -1518/720
After reducing the fraction, the answer is -253/120

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