Final answer:
The speed of the skater is 18 km/h.
Step-by-step explanation:
To find the speed of the skater, we can set up a proportion using the information given. Let's let the speed of the skater be x km/h. Since the cyclist traveled 9 km/h faster than the skater, the speed of the cyclist would be x + 9 km/h. Now, we can set up the proportion:
(x + 9 km/h)/(45 km) = x km/h)/(30 km).
To solve this proportion, we can cross-multiply and solve for x:
(x + 9 km/h)(30 km) = (x km/h)(45 km)
30x + 270 = 45x
270 = 45x - 30x
270 = 15x
x = 18
Therefore, the speed of the skater is 18 km/h.