Question 1073138
Where or when the passenger train stops for an hour will not matter.  The two trains are consuming the 1250 km distance between them.

<pre>
TRAIN         SPEED         TIME        DISTANCE
PASSENGER     r+30           4          (r+30)(4)
FREIGHT        r             5           (r)(5)
Total                                  1250
</pre>

{{{highlight_green(4(r+30)+5r=1250)}}}



{{{4r+120+5r=1250}}}

{{{9r=1250-120}}}

{{{9r=1130}}}


{{{r=125.55}}}


Or to three signif. figures,
{{{highlight(r=126)}}}-----freight train speed
{{{highlight(r+30=156)}}}-----passenger train speed