g^* = PRAThat

where g^* = the sustainable growth rate

P = the profit margin on sales, or Net Income/Sales

A = asset turnover ratio, or Sales/Total Assets

R = the retention rate, or 1 - the dividend payout rate (this is just a measure of the % of earnings a firm "retains" versus paying out as dividends)

That = the equity multiplier ratio, or Assets/Equity

Why is this calculation so important and/or how can we use this knowledge to support managerial decision-making?