Answers

Add 21/90 and 90/81

1^st number: 21/90, 2^nd number: 1 9/81

21/90 + 90/81 is 121/90.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 90 and 81 is 810
   
   Next, find the equivalent fraction of both fractional numbers with denominator 810
2. For the 1st fraction, since 90 × 9 = 810,
   21/90 = 21 × 9/90 × 9 = 189/810
3. Likewise, for the 2nd fraction, since 81 × 10 = 810,
   90/81 = 90 × 10/81 × 10 = 900/810
4. Add the two like fractions:
   189/810 + 900/810 = 189 + 900/810 = 1089/810
5. 1089/810 simplified gives 121/90
6. So, 21/90 + 90/81 = 121/90
   In mixed form: 131/90

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