Finding X components for instantaneous velocity with points on a graph

[NEAnderson90]

A test car travels in a straight line along the axis. The graph in the figure shows the car's position as a function of time. (attached figure)
Find the x component of instantaneous velocity at points A-G.

Could someone please tell me how I'm supposed to go about this problem? I know C and G are zero, but I don't know why.

 

[CompuChip]

Hi, welcome to PF.Let me check what you already know:

- So how do you determine the magnitude of the velocity from a time-distance graph?
- How do you get the x-component from the magnitude of the velocity in this case?

If you can answer both these questions you should be able to do the question, unless there are any surprises on the (as yet invisible) image.