Key phrase, "at the half-way point".
How fast needs to drive, r.
Regular 30 () d
First half 15 () d/2
Next half r () d/2
Fill in the missing time expressions.
Regular 30 (d/30) d
First half 15 d/(2*15) d/2
Next half r d/(2r) d/2
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.