$(12-4)$ Self$-$Supporting Growth Rate

Maggie's Muffins Bakery generated $$5$ million in sales during $2019,$ and its year$-$end total assets were $$2\mathrm{.}5$ million. Also, at yearend $2019,$ current liabilities were $$1$ million, consisting of $$300,000$ of notes payable, $$500,000$ of accounts payable, and $$200,000$ of accruals. Looking ahead to $2020,$ the company estimates that its operating assets must increase at the same rate as sales, its spontaneous liabilities will increase at the same rate as sales, its profit margin will be $7\%,$ and its payout ratio will be $80\%.$ How large a sales increase can the company achieve without having to raise funds externally$-$that is$,$ what is its self$-$supporting growth rate?