Partial fraction decomposition - denominator to the power of 3

Question

How to get correct partial fraction decomposition of this expression?

$$\frac{3x+3y-z}{(x+y+z)^3}$$

Answer 1

Hint

$$\frac{A}{x+y+z}+\frac{B}{(x+y+z)^2}+\frac{C}{(x+y+z)^3}$$

Now find $A,B,C$.