An exponential function is graphed in the xyxyx, y‑plane. if the graph of the function is always decreasing and has a yyy‑intercept of 202020, which of the following could be the function's equation?

17 a tourist was planning a trip by car for travelling at some constant speed for 2.5 hours. however, he found that if he increases the speed by 20 km/h he can cover the same distance in 30 minutes less time than it was planned. what was the planned speed of the tourist, in km/h?