Subtract 18/7 from 21/27, Solve 21/27

Subtract 18/7 from 21/27

1^st number: 21/27, 2^nd number: 2 4/7

21/27 - 18/7 is -113/63.

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,
21/27 = 21 × 7/27 × 7 = 147/189
Likewise, for the 2nd fraction, since 7 × 27 = 189,
18/7 = 18 × 27/7 × 27 = 486/189
Subtract the two like fractions:
147/189 - 486/189 = 147 - 486/189 = -339/189
After reducing the fraction, the answer is -113/63

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