Nate had read 400 x 20/100 = <<400*20/100=80>>80 pages.

So, he still needs to read 400 - 80 = <<400-80=320>>320 pages to finish the book.

# Answer

320
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Nate is reading a 400-page book. He finished reading 20% of the book. How many pages does he need to read to finish the book?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
320
Nate is reading a 400-page book. He finished reading 20% of the book. How many pages does he need to read to finish the book?
train