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

### Instruction:
 Rylee感到无聊，决定数一下她后院树上掉下来的叶子。第一个小时掉下来7片叶子。第二个和第三个小时，每小时掉下来4片叶子。每小时平均掉下来多少片叶子？


### Response:
 在这3个小时内，总共掉下来7 + 4 + 4 = <<7+4+4=15>>15片叶子。
每小时平均掉下来的叶子数是15 / 3 = <<15/3=5>>5片叶子。