Use the relationship between distance \(\displaystyle d\), average speed \(\displaystyle \bar{v}\) and time \(\displaystyle t\):
\(\displaystyle d=\bar{v}t\)
We are asked for time, so solve for t:
\(\displaystyle t=\dfrac{d}{\bar{v}}\)
Now, plug in the values given for \(\displaystyle d\) and \(\displaystyle \bar{v}\). What do you get?
Yes:
\(\displaystyle t=\dfrac{36\text{ mi}}{48\text{ mph}}=\dfrac{3}{4}\,\text{ hr}=45\text{ min}\).