Answers

Add 42/21 and 81/4

1^st number: 2 0/21, 2^nd number: 20 1/4

42/21 + 81/4 is 89/4.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 4 is 84
   
   Next, find the equivalent fraction of both fractional numbers with denominator 84
2. For the 1st fraction, since 21 × 4 = 84,
   42/21 = 42 × 4/21 × 4 = 168/84
3. Likewise, for the 2nd fraction, since 4 × 21 = 84,
   81/4 = 81 × 21/4 × 21 = 1701/84
4. Add the two like fractions:
   168/84 + 1701/84 = 168 + 1701/84 = 1869/84
5. 1869/84 simplified gives 89/4
6. So, 42/21 + 81/4 = 89/4
   In mixed form: 221/4

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