Imagine if the tourist could just get in the car right before the bear could catch him. This means they took the same amount of time to reach the car.
distance travelled by the tourist = d m
distance travelled by the bear = (26 + d) m
time taken by the tourist = time taken by the bear
![(d)/(4) =(26+d)/(6) \\6d=4(26+d)\\2d=104\\d=52](https://img.qammunity.org/2020/formulas/physics/middle-school/gx0khwwolj6vvvq41vrdgxkgri2toqkhqy.png)
So, the max d is 52.
Hope this helps:)