Let the number of miles Michael drove the truck be m.
Then, the cost of the drive is given by the expression,
[tex]20.99+0.85m[/tex]The actual cost is given as $134.89
Hence, we must have that
[tex]\begin{gathered} 20.99+0.85m=134.89 \\ \text{ Subtracting 20.99 from both sides we have} \\ 0.85m=113.9 \\ \text{ Dividing both sides by 0.85 we have} \\ m=\frac{113.9}{0.85}=134 \end{gathered}[/tex]Thus the number of miles is 134 miles
