Find Ratio of Segments in Triangle XYZ

[canadian_beef]

Homework Statement

For triangle XYZ, point P divides XZ in the ratio 3:1 and Q is the midpoint of XY. If R is the point of intersection of PY and QZ, find the ratio into which R divides PY.

Homework Equations

This is the only equation that may pertain to this that I can think of.
For line segment APB, vector OP= b/(a+b) OA + a/(a+b) OB, where O is any point and and b are the ratios.

The Attempt at a Solution

I really need help, this is all i can come up with.

we are looking for PR:RY

RP=1/4 RX + 3/4 RZ
RQ=1/2 RX + 1/2 RY

and RP, RZ, RQ, AND RY are vectors

help please

 

[canadian_beef]

are there any ideas? Is there something else I can tell you about this problem.