Question 893763
Assuming drove apart in opposite directions:


Let x = time in hours when they are 225 miles apart.


______________speed_______time______distance
FAST ONE______80__________x_________80x
SLOW ONE______70__________x_________70x
Total_________________________________225


{{{80x+70x=225}}}
{{{(80+70)x=225}}}
{{{150x=225}}}
{{{x=225/150}}}
{{{highlight(x=1.5)}}}