Answers

Subtract 7/42 from 81/21

1^st number: 3 18/21, 2^nd number: 7/42

81/21 - 7/42 is 155/42.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 42 is 42
   
   Next, find the equivalent fraction of both fractional numbers with denominator 42
2. For the 1st fraction, since 21 × 2 = 42,
   81/21 = 81 × 2/21 × 2 = 162/42
3. Likewise, for the 2nd fraction, since 42 × 1 = 42,
   7/42 = 7 × 1/42 × 1 = 7/42
4. Subtract the two like fractions:
   162/42 - 7/42 = 162 - 7/42 = 155/42
5. In mixed form: 329/42

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