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

### Instruction:
 如果你把一个数翻倍然后加上5，那么结果比原数的一半多20。原数是多少？


### Response:
 设原数为x。
2*x+5=20+x/2
4*x-x/2=15
8*x-x=30
7*x=30
x=<<4=4>>4