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

### Instruction:
 艾娃在她的后院种了9棵苹果树。这比莉莉种的多3棵。他们总共种了多少棵苹果树？


### Response:
 由于艾娃种的苹果树比莉莉多3棵，莉莉在她的后院种了9-3 = <<9-3=6>>6棵苹果树。
他们总共种了6+9 = <<6+9=15>>15棵苹果树。