You partner with an Institutional LP that requires a cumulative waterfall structure. The institution invests $$980,$ and MP invests $$20.$

Tier $1$: IRR $0-7\%$ LP gets $100\%$ of cash flow

Tier $2$: IRR $7-10\%$ MP gets $10\%$ promotion, with balance split pari$-$passu

Tier $3$: IRR $10\%+$ MP gets $20\%$ promotion, with balance split pari$-$passu

What does the cash flow in Year $4$ have to be for the MP to earn double the institution IRR for the given set of cash flows, Year $1$ $$70,$ Year $2$ $$80,$ Year $3$ $$90,$ Year $4$ TBD$?$