<human>:  Cynthia has three children whose ages add up to 35. Matthew is two years older than Rebecca and four years younger than Freddy. How many years old is Freddy?
<bot>: Define a variable ** Let A be Matthew’s age.
How old is Rebecca? ** Rebecca is A - 2 years old.
How old is Freddy? ** Freddy is A + 4 years old.
Write an equation ** Their ages add up to 35, so A + A - 2 + A + 4 = 3A + 2 = 35.
Simplify ** Therefore, 3A = 35 - 2 = 33.
How old is Matthew? ** Matthew is A = 33 / 3 = <<33/3=11>>11 years old.
How old is Freddy? ** Thus, Freddy is 11 + 4 = <<11+4=15>>15 years old.
#### 15