A tourist being chased by an angry bear is running in a straight line toward his car at a speed of 4.77 m/s. The car is a distance d away. The bear is 17.8 m behind the tourist and running at 6.68 m/s. The tourist reaches the car safely. What is the maximum possible value for d?

If bear's time and tourist's time to reach the car are the same, you have the maximum possible d.

Write that as an equation and solve for d. (d is the initial distance from tourist to car)

Time to reach car
=(d + 17.8)/6.68 = d/4.77
6.68 d = 4.77 d + 84.91
1.91 d = 84.91
d = 44.46 m

Both reach the car in 9.32 s