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

### Instruction:
 鸟篱笆上的鸟的数量是鸟篱笆上的鸟的两倍再加上十只，等于50只。鸟篱笆上有多少只鸟？


### Response:
 设鸟篱笆上的鸟的数量为x。我们知道10 + 2*x = 50。
两边同时减去10，我们得到2*x = 50 - 10 = 40
两边同时除以2，我们得到x = 40/2 = <<40/2=20>>20