Final answer:
Mrs. Kreutzer has read a total of 540 pages in two weeks. Given that the Harry Potter book has 689 pages in total, she would still need to read 149 pages to finish the book in 3 weeks.
Step-by-step explanation:
To solve this problem, we need to subtract the number of pages Mrs. Kreutzer has already read from the total number of pages in the book. Firstly, Mrs. Kreutzer read 203 pages in the first week and 337 pages in the second week. Hence, the total number of pages she has read in two weeks is 203 + 337 = 540 pages.
Next, considering the Harry Potter book has a total of 689 pages, the remaining pages she still needs to read to finish the book in 3 weeks is 689 - 540 = 149 pages.
Therefore, Mrs. Kreutzer has to read 149 pages if she wants to finish the book in 3 weeks.
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