에러! 자바스크립트가 활성화되어야 합니다!
\begin{align} NPV &=-C_{0}+\sum_{i=1}^{t}\frac {C_{i}}{(1+r)^{i}}\\ \\ PI &=\frac{\sum_{i=1}^{t}\frac {C_{i}}{(1+r)^{i}}}{C_{0}}\\ \end{align}