Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
Tom’s cat is 8 years old.  His rabbit is half the age of his cat.  His dog is three times as old as his rabbit.  How old is the dog?

### Response:
Tom’s rabbit is 1/2 * 8 years = <<1/2*8=4>>4 years old.
His dog is 3 * 4 years = <<3*4=12>>12 years old.
#### 12