Answers

Add 90/20 and 63/21

1^st number: 4 10/20, 2^nd number: 3 0/21

90/20 + 63/21 is 15/2.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 20 and 21 is 420
   
   Next, find the equivalent fraction of both fractional numbers with denominator 420
2. For the 1st fraction, since 20 × 21 = 420,
   90/20 = 90 × 21/20 × 21 = 1890/420
3. Likewise, for the 2nd fraction, since 21 × 20 = 420,
   63/21 = 63 × 20/21 × 20 = 1260/420
4. Add the two like fractions:
   1890/420 + 1260/420 = 1890 + 1260/420 = 3150/420
5. 3150/420 simplified gives 15/2
6. So, 90/20 + 63/21 = 15/2
   In mixed form: 71/2

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