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

### Instruction:
 一本笔记本的价格是一支钢笔的三倍。如果一支钢笔的价格是1.50美元，莱尔买4本笔记本要付多少钱？


### Response:
 一本笔记本的价格是1.50美元 x 3 = 4.50美元。
四本笔记本的价格是4.50美元 x 4 = 18美元。