You have a game named Rollic. Currently, there are $2$ platforms you are doing UA activity. These $2$ sources show different

performance metrics like below. We have $30\%$ gross margin goal at day $7.$ In that matter, what max CPI limits would you set for

these $2$ sources? Please explain.

Source $1$:

Spent: $$5000($Spent in day $0.$ No more spent will be made next days$)$

Number of rewarded video ad per user per day: $5$

Number of interstitial ad per user per day: $4$

Rewarded video ad eCPM: $$38$

Interstitial ad eCPM: $$22$

Retention rate $($You may assume keeping $100\%$ of users at day $0)$

Source $2$:

Spent: $$2500($Spent in day $0.$ No more spent will be made next days$)$

Number of rewarded video ad per user per day: $7$

Number of interstitial ad per user per day: $3$

Rewarded video ad eCPM: $$42$

Interstitial ad eCPM: $$25$

Retention rate $($You may assume keeping $100\%$ of users at day $0)$