Problem $4-18$ Growth and Profit Margin $[$LO$3]$

Gamgee Company wishes to maintain a growth rate of $11\mathrm{.}8$ percent per year, a debt$-$equity ratio of $1\mathrm{.}7,$ and a dividend payout ratio of $20$ percent. The ratio of total assets to sales is constant at $\mathrm{.}89.$ What profit margin must the firm achieve?