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

### Instruction:
 艾玛每个上学日午餐都买2瓶牛奶。她周末不上学。她3周买了多少瓶牛奶？


### Response:
 一周有5个上学日：每周5天 x 每天2瓶牛奶 = 10瓶牛奶
最后3周的瓶数是3周 x 每周10瓶 = <<3*10=30>>30瓶牛奶