Addison's age is three times Brenda's age. Janet is six years older than Brenda. Addison and Janet are twins. How old is Brenda?
To solve this problem, I need to find a way to express the relationship between the three ages in terms of one variable. Since Addison and Janet are twins, they have the same age, so I can write A = J. Then, using the information that Addison is three times Brenda's age, I can write A = 3B. And using the information that Janet is six years older than Brenda, I can write J = B + 6. Now I have three equations with three variables, but I can eliminate one of them by substituting A for J in the third equation, since they are equal. This gives me A = B + 6. Now I have two equations with two variables, but I can eliminate another one by substituting 3B for A in the second equation, since they are also equal. This gives me 3B = B + 6. Now I have one equation with one variable, which I can solve by subtracting B from both sides. This gives me 2B = 6, or B = 3. This means that Brenda is 3 years old. To check my answer, I can plug it back into the original equations and see if they are all true. A = 3B, so A = 3 * 3 = 9. This is Addison's age. J = B + 6, so J = 3 + 6 = 9. This is also Janet's age, and it matches Addison's age, since they are twins. So the equations are consistent, and Brenda is 3 years old. 