Answers

Add 81/21 and 10/90

1^st number: 3 18/21, 2^nd number: 10/90

81/21 + 10/90 is 250/63.

Steps for adding 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,
   10/90 = 10 × 7/90 × 7 = 70/630
4. Add the two like fractions:
   2430/630 + 70/630 = 2430 + 70/630 = 2500/630
5. 2500/630 simplified gives 250/63
6. So, 81/21 + 10/90 = 250/63
   In mixed form: 361/63

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