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?
Let's be accurate as possible and think first.
19
From Monday to Tuesday, Nico reads a total of 20 + 12 = 32 pages.

On Wednesday, he read a total of 51 - 32 = 19 pages.

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So, the answer is 19