Answer:
Mitchell's dog is 3 years old
Step-by-step explanation:
9 x 1/3 = 3
9 + 3 = 12
To solve this I just thought of the multiples of three under 12 that if added to 3 are equal to 12 to find Katie's cat age. The multiples of three under 12 are 3, 6 and 9. It couldn't be 3 and 6+3=9 so it had to be 9. So if Katie's cat is 9, you just multiply 9 by 1/3 or divide it by 3 to find Mitchell's dog age.
