Consider that the speed (s), distance (d) travelled, and time (t) taken to travel the distance are related as,
[tex]\begin{gathered} \text{ Speed}=\frac{\text{ Distance}}{\text{Time}} \\ s=\frac{d}{t} \end{gathered}[/tex]Given that the speed is 59 miles per hour,
[tex]s=59[/tex]Also, the time is given as 'x' hours,
[tex]t=x[/tex]Substitute the values in the relation,
[tex]59=\frac{d}{x}[/tex]Multiply by 'x' both sides of the equation,
[tex]\begin{gathered} 59\cdot x=\frac{d}{x}\cdot x \\ 59x=d \end{gathered}[/tex]So, it is found that,
[tex]d=59x[/tex]Thus, the expression for distance travelled in 'x' hours with the speed of 59 mph is,
[tex]d=59x[/tex]