A cyclist traveled 9 kilometers per hour faster than an in-line skater. In the time it took the cyclist to travel 45 kilometers, the skater had gone 30 kilometers. What's the speed of the skater?

18 kmh

Step-by-step explanation:

Given: Speed of cyclist is 9 km/h more than skater´s speed.

           Distance covered at the given time by cyclist is 45 km and by skater is 30 km.

Let´s assume the speed of skater be "x"

∴ Speed of cyclist will be

Remember; time=

We know the time taken by both cyclist and skater are same.

∴ we can form an equation to find the speed of skater.

Time taken by cyclist= time taken by skater

⇒

Multiplying both side by

⇒

Using distributive property of multiplication

⇒

Subtracting both side by 30x

⇒

Dividing both side by 15

⇒

∴

Hence, speed of the skater is 18 kmh

correct answer:

b.(19,-2)

b

step-by-step explanation: