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

### Instruction:
 Sam went for a run in the morning. In the afternoon, he went grocery shopping and walked twice the distance through the store as he had run that morning. That evening, he went on a bike ride with his family and biked for 12 miles. In all, he went 18 miles that day. How many miles was Sam’s morning run?


### Response:
 Sam先晨跑，然后骑自行车，所以他那天总共走了18英里。
Sam在商店里走的距离是他晨跑的两倍，骑自行车骑了12英里，所以他的总距离是2x + 12 = 18。
2x = 18 - 12 = <<18-12=6>>6
x = 6/2 = <<6/2=3>>3
Sam晨跑了3英里。