Geometric and Arithmetic series question

The question is:

The numbers *x, y, z* are succesive terms of a G.S with the sum of the three terms equal to 9. When taken in the order *y, x ,z* the numbers form an A.S. Find the values of *x, y, z*?

G.S $\displaystyle 9 = x(r^3-1)/(r-1)$

A.S $\displaystyle 9 =(3/2) * (2x + (3-1)*d$

So I have that the sum of the G.S and A.S are equal and therefore I can say that the equations are equal to each other but i just don't know where to go from here or if I'm correct...

Thanks for any help you can give me