Answers

Add 21/84 and 9/40

21/84 + 9/40 is 19/40.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 84 and 40 is 840
   
   Next, find the equivalent fraction of both fractional numbers with denominator 840
2. For the 1st fraction, since 84 × 10 = 840,
   21/84 = 21 × 10/84 × 10 = 210/840
3. Likewise, for the 2nd fraction, since 40 × 21 = 840,
   9/40 = 9 × 21/40 × 21 = 189/840
4. Add the two like fractions:
   210/840 + 189/840 = 210 + 189/840 = 399/840
5. 399/840 simplified gives 19/40
6. So, 21/84 + 9/40 = 19/40

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