so she reads for 5 hours every day for 15 days, how many hours is that? well is just 5*15, or 75 hours.
so, she reads 900 pages in 75 hours, how many pages does she do in 1 hour?
[tex]\bf \begin{array}{ccll}
pages&hours\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
900&75\\
p&1
\end{array}\implies \cfrac{900}{p}=\cfrac{75}{1}\implies \cfrac{900\cdot 1}{75}=p[/tex]
