Thread: Please help me solving the equation

Dear Math-Crack,

I really (!!!) would appreciate you help in solving the following equating for "w":
r=w*7.8-i / (sqr(7.8²+i²-2*w*7.8*i))

Sqr stands for square root. "/" for division
This is a version of the equation for the so called "part whole correlation" in Statistics (r=part whole correlation).
I want to reverse the "part whole correltion". To do that I "simply" have to solve the equation for w but I did not succeed!

Any help would be appreciated!

sincerly,
M@ne

Because, shame on me, I made a fault typing the formula:

It has to be that way:

Any Ideas?