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

### Instruction:
Nico borrows 3 books from the library on Monday.  On Monday, he reads the first book with a total of 20 pages.  On Tuesday, he reads the second book with a total of 12 pages.  On Wednesday, he reads the third book.  If he has read a total of 51 pages from Monday to Wednesday, how many pages did he read on Wednesday?

### Response:
Nico read 20 pages on Monday, 12 pages on Tuesday, and 19 pages on Wednesday (51 total pages - 20 pages - 12 pages = 19 pages).
#### 19

