That's not a ratio... but since you asked for a hint...

Expand all the brackets and collect like terms, you should get...

Recall that ? Using this we get...

Now, assuming a, b, c, x, y and z are all real... we have 3 square terms adding to become 0. Since a square term is never non-negative... all the terms must be 0.

So we have which gives or .

Similarly, gives ,

and gives .

Thus

.