Answers

Subtract 8/90 from 81/21

1^st number: 3 18/21, 2^nd number: 8/90

81/21 - 8/90 is 1187/315.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 90 is 630
   
   Next, find the equivalent fraction of both fractional numbers with denominator 630
2. For the 1st fraction, since 21 × 30 = 630,
   81/21 = 81 × 30/21 × 30 = 2430/630
3. Likewise, for the 2nd fraction, since 90 × 7 = 630,
   8/90 = 8 × 7/90 × 7 = 56/630
4. Subtract the two like fractions:
   2430/630 - 56/630 = 2430 - 56/630 = 2374/630
5. After reducing the fraction, the answer is 1187/315
6. In mixed form: 3242/315

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