I need to solve $2$ questions for a mobile application. I have $8$ days of data. The data I have for each date; There are Marketing Cost, Install $($Paid$),$ Total Install, DAU, D$1$ Retention, D$2$ Retention, D$3$ Retention, D$7$ Retention, Revenue. Accordingly, how can I calculate these two questions?

$1.$ What is D$14$ LTV$?$

$2.$ What should be the maximum CPI $($Cost per Install$)$ to reach break$-$even point?