One pedestrian covered the path in 15 minutes, and the second pedestrian covered the same path in 1/3 hour

One pedestrian covered the path in 15 minutes, and the second pedestrian covered the same path in 1/3 hour. Determine the speed of the first pedestrian if the speed of the second is 4.5 km / h.

Given:
s1 = s2 = s = const (the path is the same for two pedestrians);
t1 = 15 minutes = 1/4 hour = 0.25 hours (Since the path in this task is measured in kilometers, then the time should be measured in hours);
t2 = 1/3 hours.;
v2 = 4.5 km / min.
Find:
v1 =?
Solution:
1) s2 = s = v2 * t2
s2 = 4.5 * (1/3) = 1.5 (km) – the second pedestrian passed.
2) v1 = s1 / t1 = s / t1
1.5 / 0.25 = 6 (km / h) – the first pedestrian passed in the same time.
Answer: the speed of the first pedestrian is 6 km / h