Dotty is 51 years old and Esmerelda is 23. How many years ago was Dotty 3 times Esmerelda's age?

9 years ago.

Step-by-step explanation:

Dotty is 51 years old and Esmerelda is 23 now.

Now, x years ago the age of Dotty was (51 - x) years and the age of Esmerelda was (23 - x) years.

Assume that x years ago Dotty was 3 times Esmerelda's age.

So, we can write the equation as

3 (23 - x) = 51 - x

⇒ 69 - 3x = 51 - x

⇒ 69 - 51 = 3x - x

⇒ 18 = 2x

⇒ x = 9 years.

Therefore, 9 years ago Dotty was 3 times Esmerelda's age. (Answer)