Given: Mitchell's dog is 1/3 as old as Katie's cat. The sum of their ages is 12 years.
Required: To find out how old is Mitchell's dog.
Explanation: Let Mitchell's dog be x years old. Then Katie's cat is 3x. Now according to the question-
[tex]\begin{gathered} x+3x=12 \\ 4x=12 \\ x=\frac{12}{4} \\ x=3 \end{gathered}[/tex]Hence Mitchell's dog is 3 years old.
Final Answer: Mitchell's dog is 3 years old.
