Feldspar Inc. is considering the capital structure for a new division. Management has been given the following cost information:

Debt$/$assets

kd$($BT Cost of Debt$)$

ke$($Cost of Equity$)$

$\mathrm{.}30$

$6\mathrm{.}75\%$

$15\%$

$\mathrm{.}40$

$7\mathrm{.}25\%$

$15\mathrm{.}7\%$

$\mathrm{.}50$

$8\%$

$16\mathrm{.}5\%$

$\mathrm{.}60$

$9\mathrm{.}5\%$

$17\mathrm{.}6\%$

$\mathrm{.}70$

$11\mathrm{.}5\%$

$19\mathrm{.}5\%$

Based on this information, what capital structure $($debt$/$asset ratio$)$ should management accept? Assume the marginal tax rate is $25\%.$ Please show the work