$.$S$.$ Robotics Inc. has a current capital structure of $30\%$ debt and $70\%$ equity. Its current before$-$tax cost of debt is $6\%,$ and its tax rate is $45\%.$ It currently has a levered beta of $1\mathrm{.}25.$ The risk$-$free rate is $3\mathrm{.}5\%,$ and the risk premium on the market is $7\%.$U$.$S$.$ Robotics Inc. is considering changing its capital structure to $60\%$ debt and $40\%$ equity. Increasing the firm$$s level of debt will cause its before$-$tax cost of debt to increase to $8\%.$

First, solve for U$.$S$.$ Robotics Inc.$$s unlevered beta?

Relever U$.$S$.$ Robotics Inc.$$s beta using the firm$$s new capital structure.

Use U$.$S$.$ Robotics Inc.$$s levered beta under the new capital structure, to solve for its cost of equity under the new capital structure.

What will the firm$$s weighted average cost of capital $($WACC$)$ be if it makes this change in its capital structure?

$6\mathrm{.}0\%$

$10\mathrm{.}1\%$

$9\mathrm{.}2\%$

$8\mathrm{.}7\%$