Question 1005182
Key phrase, "at the half-way point".


How fast needs to drive, r.

<pre>
Regular            30          ()       d
First half         15         ()       d/2
Next half          r          ()       d/2
</pre>


Fill in the missing time expressions.


<pre>
Regular            30         (d/30)        d
First half         15         d/(2*15)       d/2
Next half          r         d/(2r)       d/2
</pre>
Ivan will be late, and can NOT catch the train.  He used up all the needed travel time at the half-way point of the trip.