Let t hours be the time the second car is driving untill it overtakes the first car. The nfirst car is [tex]t-1\dfrac{1}{2}[/tex] hours on the road.
If the lead car is going 60 mph, then for the [tex]t-1\dfrac{1}{2}[/tex] hours it will go the distance
[tex]60\cdot(t-1\frac{1}{2})\ m.[/tex]
If the second place car is going 70 mph, then for the [tex][/tex] hours it will go the distance
[tex]70\cdot t\ m.[/tex]
These distances are equal, then
[tex]60(t-1\frac{1}{2})=70t,\\ \\60t-60\cdot \frac{3}{2}=70t,\\ \\10t=90,\\ \\t=9\ hours.[/tex]
Answer: 9 hours
