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

### Instruction:
 萨米在操场上找到了3只蜘蛛。亨特看到了12只蚂蚁爬墙。明在沙箱里发现了8只瓢虫，并看到其中2只飞走了。操场上还剩下多少昆虫？


### Response:
 孩子们找到了3 + 12 + 8 = <<3+12+8=23>>23只昆虫。
瓢虫飞走后，剩下23 - 2 = <<23-2=21>>21只昆虫。