Subtract 90/81 from 2/21, Solve 2/21

Subtract 90/81 from 2/21

1^st number: 2/21, 2^nd number: 1 9/81

2/21 - 90/81 is -64/63.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 81 is 567

Next, find the equivalent fraction of both fractional numbers with denominator 567
For the 1st fraction, since 21 × 27 = 567,
2/21 = 2 × 27/21 × 27 = 54/567
Likewise, for the 2nd fraction, since 81 × 7 = 567,
90/81 = 90 × 7/81 × 7 = 630/567
Subtract the two like fractions:
54/567 - 630/567 = 54 - 630/567 = -576/567
After reducing the fraction, the answer is -64/63

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