Given that m is the number of miles driven by the truck.
From the information given,
The charge by Company A would be:
[tex]0+80\times m=80m[/tex]The charge by Company B would be:
[tex]75+70\times m=75+70m[/tex]If company A charges at least as much as company B, then
[tex]A\ge B[/tex]Therefore,
[tex]\begin{gathered} 80m\ge75+70m \\ 80m-70m\ge75 \\ 10m\ge75 \\ m\ge\frac{75}{10}=7.5 \\ \text{The mileage is 7.5}\frac{miles}{cent} \end{gathered}[/tex]