For what value of P would the NPV of the following cash flow series be zero at an interest rate of 12% per year?

MUST BE IN EXCELL AND SHOW THE FORMULAS

\begin{tabular}{|c|c|c|} \hline Month & Deposits & Withdrawals \\ \hline 0 & -100 & 0 \\ \hline 1 & -200 & 0 \\ \hline 2 & 7P & 0 \\ \hline 3 & 0 & 300 \\ \hline 4 & 0 & 2.5P \\ \hline 5 & 0 & 100 \\ \hline 6 & -500 & 0 \\ \hline 7 & -600 & 0 \\ \hline 8 & -1700 & 0 \\ \hline 9 & 0 & 2P \\ \hline 10 & 0 & 0 \\ \hline \end{tabular}