How to write an equation?

Question

I have a graph that shows karrie rides her bicycle 20 km per every 1 hour.  The question is Write an equation that relates the distance, in kilometers, Karrie rides, y, and the time, in hours, she rides, x.  I'm lost. Can anyone explain this to me since my teacher never explains anything?  Thank you.

Answer 1

distance = rate*time ... d = rt

 

distance = y

rate = 20 kph

time = x 

 

y = 20x