Mathematics

Question

Riley is 3 years older than his sister. Which of the following expressions shows the sum of their ages if s represents Riley's sister's age?
3s
s + 3
2(s + 3)
2s + 3

2 Answer

  • 2s+3 because Riley is represented by 3+s and the other s represents Riley's sister. 
  • 2s+3 Why? because Riley is s+3 (His sister's age + 3). If we add them together we have Riley (s+3) and sister (s) which is (s+3)+(s). That is the same as s+s+3 which you can write as 2s+3


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