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

### Instruction:
 特伦特从家走了4个街区到公交车站。他乘公交车去图书馆走了7个街区。后来，他以同样的方式回家。特伦特总共走了多少个街区？


### Response:
 去图书馆的路上走的街区数是4 + 7 = <<4+7=11>>11。
特伦特来回总共走了11 × 2 = <<11*2=22>>22个街区。