Question

A student reads 2⁄5 of a book in 45 minutes. How much of the book will be read if the student reads at the same speed for 70 minutes?

Answer 1

`\bf \begin{array}{ccllll} read&minutes\\ \textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\ (2)/(5)&45\\ x&70 \end{array}\implies \cfrac{(2)/(5)}{x}=\cfrac{45}{70}\implies \cfrac{(2)/(5)}{(x)/(1)}=\cfrac{45}{70} \\\\\\ \cfrac{2}{5}\cdot \cfrac{1}{x}=\cfrac{45}{70}\implies \cfrac{2}{5x}=\cfrac{45}{70}`

solve for "x"