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

### Instruction:
 斯泰西是一位高中微积分老师。她布置了45个作业题。选择题的数量是解答题的两倍，而解答题比判断题多7个。有多少个判断题？


### Response:
 让x代表判断题的数量
解答题：x+7
选择题：2(x+7)=2x+14
总数：x+x+7+2x+14=45
4x+21=45
4x=24
x=<<6=6>>6个判断题