What is the World Line Diagram for Light Pulses in Two Frames?

[Andy93]

Homework Statement

A light source at the origin of the O frame emits short pulses of light in interval of $\tau$ as measured in O. An observer located at the origin of the O' frame which moves at velocity v with respect to O along the x-axis, receives these light pulses.
Use a world line diagram to show the receipt of two consecutive pulses as measured in O if the first is emitted when the frame origins coincide. Show that measured in O the pulses are received at the origin of O' with the temporal separation of (c$\tau$)/(c-v) and spatial separation of (c$\tau$v)/(c-v).

Homework Equations

The Attempt at a Solution

The pulses of light travel at velocity c
The receiver travels at velocity v
I have drawn the world line (t-x plot) and I'm pretty sure it's Δt and Δx i need to calculate but I'm not sure how to go about it.
http://img24.imageshack.us/img24/4083/z559.png

 

[vela]

Your diagram looks good. Now you're trying to find where the two lines intersect. This is just like what you did in algebra class, except this time the variables are x and t instead of x and y.

Start by figuring out the equations for the two lines.

 

[Andy93]

I didn't realize it would be so simple, thanks a lot for the help. It worked out perfectly.