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

### Instruction:
 在我的学校，今年学生人数增加了20%。今年的学生人数是960人。去年有多少学生？


### Response:
 假设去年的学生人数为X。今年的学生人数为X+X*20% = 960
合并同类项，得到X*1.2 = 960
两边除以1.2，得到X = 800人。