Equation in multiple lines: Latex eqnarray

\begin{eqnarray}
CCI_{n} &=& PLA*w_{1} + PFT*w_{2} + MCD*w_{3} + \nonumber \\
&& {} + SDCD*w_{4} + MHA*w_{5} + \nonumber \\
&& {} + SDHA*w_{6} + MS*w_{7} + SDS*w_{8}
\label{results_CCI_equation}
\end{eqnarray} \\ \\

Reference: Latex Cookbook