Answers

Add 21/84 and 18/45

21/84 + 18/45 is 13/20.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 84 and 45 is 1260
   
   Next, find the equivalent fraction of both fractional numbers with denominator 1260
2. For the 1st fraction, since 84 × 15 = 1260,
   21/84 = 21 × 15/84 × 15 = 315/1260
3. Likewise, for the 2nd fraction, since 45 × 28 = 1260,
   18/45 = 18 × 28/45 × 28 = 504/1260
4. Add the two like fractions:
   315/1260 + 504/1260 = 315 + 504/1260 = 819/1260
5. 819/1260 simplified gives 13/20
6. So, 21/84 + 18/45 = 13/20

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