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

### Instruction:
 二年级有20个男生和11个女生，三年级的人数是二年级的两倍。二年级和三年级一共有多少学生？


### Response:
 二年级有20 + 11 = <<20+11=31>>31个学生。
三年级有31 x 2 = <<31*2=62>>62个学生。
总共有31 + 62 = <<31+62=93>>93个学生。