ANSWER
[tex]\frac{3}{4}\text{book/hour}[/tex]EXPLANATION
We want to rewrite the given fraction as a unit rate:
[tex]\frac{\frac{1}{4}\text{book}}{\frac{1}{3}\text{hour}}[/tex]To do this, simplify the fraction:
[tex]\begin{gathered} \frac{1}{4}\div\frac{1}{3} \\ \Rightarrow\frac{1}{4}\cdot\frac{3}{1} \\ \Rightarrow\frac{3}{4}\text{book/hour} \end{gathered}[/tex]That is the unit rate.