Answers

Subtract 81/28 from 42/20

1^st number: 2 2/20, 2^nd number: 2 25/28

42/20 - 81/28 is -111/140.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 20 and 28 is 140
   
   Next, find the equivalent fraction of both fractional numbers with denominator 140
2. For the 1st fraction, since 20 × 7 = 140,
   42/20 = 42 × 7/20 × 7 = 294/140
3. Likewise, for the 2nd fraction, since 28 × 5 = 140,
   81/28 = 81 × 5/28 × 5 = 405/140
4. Subtract the two like fractions:
   294/140 - 405/140 = 294 - 405/140 = -111/140

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