Question 1202491
<pre>
                   SPEED        TIME        DISTANCE
EXPRESS             r             20           d
FREIGHT             r-10          25           d
</pre>
Each train, same distance d.
{{{20r=25(r-10)}}}


{{{20r=25r-25*10}}}

{{{25r-20r=25*10}}}

{{{(25-20)r=25*10}}}

{{{highlight(r=(25*10)/(25-20))}}}


{{{system(EXPRESS,FREIGHT)}}}------{{{system(r=50,r-10=40)}}}