As it is a rate then you can solve the problem solving in the following way
[tex]\begin{gathered} \frac{12\text{ miles}}{1.5\text{ hours}}=\frac{x\text{ miles}}{1\text{ hour}} \\ \text{Multiply by 1 hour on both sides of the equation} \\ \frac{12\text{ miles}}{1.5\text{ hours}}\cdot1\text{ hour}=\frac{x\text{ miles}}{1\text{ hour}}\cdot1\text{ hour} \\ 8\text{ miles = x} \end{gathered}[/tex]Therefore, Joseph was a speed of 8 miles per hour.
