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

### Instruction:
 汤米的铅笔盒里有13个物品。钢笔的数量是铅笔的两倍，还有一个橡皮擦。有多少支铅笔？


### Response:
 计算钢笔和铅笔的总数。有13个物品 - 1个橡皮擦 = <<13-1=12>>12支钢笔和铅笔。
有12个物品 / 3 = <<12/3=4>>4支铅笔。