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

### Instruction:
 汤姆的猫8岁了。他的兔子是他猫的一半年龄。他的狗比他的兔子大三倍。狗多大了？


### Response:
 汤姆的兔子是1/2 * 8岁 = <<1/2*8=4>>4岁。
他的狗是3 * 4岁 = <<3*4=12>>12岁。