We have the following:
First we must get the equations of each company, like this
Company A:
[tex]A=85+0.10\cdot x[/tex]Company B:
[tex]B=55+0.60\cdot x[/tex]Where x is every mile driven.
Now, A < B, replacing:
[tex]\begin{gathered} 85+0.10x<55+0.60x \\ -0.6x+0.1x<55-85 \\ -0.5x<-30 \\ x>\frac{30}{0.5} \\ x>60 \end{gathered}[/tex]That is, after 60 miles, company A will not charge more than company B