\mbox{NPV} =  - \mbox{I}_0 + \mbox{DCF}  =  - \mbox{I}_0 + \sum_{i=1}^n \frac{\mbox{FCF}_i}{(1+r)^i} = \sum_{i=0}^n \frac{\mbox{FCF}_i}{(1+r)^i}

\mbox{FCF}_i = (\mbox{NETBACK}_i - \mbox{OPEX_i) * \mbox{TAX}_{income}

\mbox{NETBACK}_i = \mbox{REV}_i * \mbox{TAX}_{SLS}

\mbox{OPEX}_i = \mbox{COGS}_i + \mbox{SAGS}_i

\mbox{COGS}_i = \mbox{q}_i * \mbox{C/q}

\mbox{REV}_i = \mbox{q}_i * \mbox{R/q}