We must first consider the inequality
[tex]0+0.7m>70+0.6m[/tex]This is because company A has no initial fee and charges 70 cents per mile driven, and company B has a $70 initial fee and charges 60 cents per mile driven, and we're interested in seeing when company's A rate will be higher than company's B.
So, we solve the inequality.
[tex]0.7m>0.6m+70[/tex][tex]0.1m>70[/tex][tex]m>700[/tex]Thus, company A will charge more than company B for distances longer than 700 miles.