Answers

Subtract 21/42 from 20/75

20/75 - 21/42 is -7/30.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 75 and 42 is 1050
   
   Next, find the equivalent fraction of both fractional numbers with denominator 1050
2. For the 1st fraction, since 75 × 14 = 1050,
   20/75 = 20 × 14/75 × 14 = 280/1050
3. Likewise, for the 2nd fraction, since 42 × 25 = 1050,
   21/42 = 21 × 25/42 × 25 = 525/1050
4. Subtract the two like fractions:
   280/1050 - 525/1050 = 280 - 525/1050 = -245/1050
5. After reducing the fraction, the answer is -7/30

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