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

### Instruction:
 斯泰西有32颗浆果。史蒂夫拿走了斯泰西的4颗浆果，而且比斯泰西开始时少了7颗浆果。史蒂夫开始有多少颗浆果？


### Response:
 设史蒂夫开始有x颗浆果
x+4=32-7
x+4=25
x=<<21=21>>21颗浆果