Question 996217
RT=D uniform travel rate rule relates rate, time, distance.


<pre>
           speed     time   distance
BUS         40        ()     ()
TRAIN      110        ()     ()
Total                       210
</pre>
You could either pick  variables for each of the missing times or pick variables for each missing distance, but maybe you need more information.

<pre>
           speed     time   distance
BUS         40        ()     (x)
TRAIN      110        ()     (210-x)
Total                       210
</pre>

The choices listed are strange; You need more information.
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MAYBE you meant total time was 312 hours?