Subtract 80/7 from 90/27, Solve 3 9/27

Subtract 80/7 from 90/27

1^st number: 3 9/27, 2^nd number: 11 3/7

90/27 - 80/7 is -170/21.

Find the least common denominator or LCM of the two denominators:
LCM of 27 and 7 is 189

Next, find the equivalent fraction of both fractional numbers with denominator 189
For the 1st fraction, since 27 × 7 = 189,
90/27 = 90 × 7/27 × 7 = 630/189
Likewise, for the 2nd fraction, since 7 × 27 = 189,
80/7 = 80 × 27/7 × 27 = 2160/189
Subtract the two like fractions:
630/189 - 2160/189 = 630 - 2160/189 = -1530/189
After reducing the fraction, the answer is -170/21

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