Question 1008014
<pre>
             rate        time       distance
SLOW          r           4         r*4
FAST         (3/2)r       4        (3/2)r*4
Difference                            80
</pre>
{{{highlight_green((3/2)*4*r-4r=80)}}}
{{{(3/2)r-r=20}}}
{{{r(3/2-1)=20}}}
{{{r/2=20}}}
{{{highlight(r=40)}}}  and the fast car  goes 60 miles per hour.