Find the measure of a. 84 b. 168 c. 192 d. 96

Antti entered a -kilometer race. His goal is to finish in one hour. He starts off sprinting, and completes the first  kilometers of the race at an average speed of  kilometers per hour.

To achieve his goal of a one-hour finish time, what average speed (in kilometers per hour) must Antti maintain for the last  kilometers of the race?

Enter your answer as a number in decimal form, without units.Hint(s):

Not sure what the question is but i hope this x = years100 * x