Answers

Subtract 21/27 from 18/42

18/42 - 21/27 is -22/63.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 42 and 27 is 378
   
   Next, find the equivalent fraction of both fractional numbers with denominator 378
2. For the 1st fraction, since 42 × 9 = 378,
   18/42 = 18 × 9/42 × 9 = 162/378
3. Likewise, for the 2nd fraction, since 27 × 14 = 378,
   21/27 = 21 × 14/27 × 14 = 294/378
4. Subtract the two like fractions:
   162/378 - 294/378 = 162 - 294/378 = -132/378
5. After reducing the fraction, the answer is -22/63

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