She need 6 hours to finish the book.
Calculations:
Given that,
Gwendolyn has already read 130 pages of her 400-page summer reading book.
Remaining number of pages \(=400-130=270\) pages.
and she reads at an average rate of 45 pages per hour.
So that, number of hours she needs to finish book is,
\(=\frac{270}{45}=6hours\)
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