Tobin Supplies Company expects sales next year to be $500,000. Inventory and accounts receivable will increase $90,000 to accommodate this sales level. The company has a steady profit margin of 12% with a 40% dividend payout. How much external financing will Tobin Supplies Company have to seek? assume there is no increase in liabilities other than that which will occur with the external financing.

I found the formula EFN= New investments- Addition to Retained Earnings, but I feel like that one isn't right. Which formula would I use for this problem?