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

### Instruction:
 约翰和山姆饿了，所以他们点了一份切成12块的超大比萨。约翰吃了3块，而山姆吃了约翰吃的两倍。还剩下多少块比萨？


### Response:
 山姆吃了2*3 = <<2*3=6>>6块比萨。
他们一共吃了3+6 = <<3+6=9>>9块比萨。
还剩下12-9 = <<12-9=3>>3块比萨。