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

### Instruction:
 约翰种了一个3x4的果树园。每棵树结5个苹果。他每个苹果卖0.5美元。他能赚多少钱，以美元计算？


### Response:
 他有3x4=<<3*4=12>>12棵树
所以他有12x5=<<12*5=60>>60个苹果
所以他卖掉的苹果总共是60x0.5=$<<60*.5=30>>30