Aphid Corp. will finance its next major expansion with $60\%$ debt, $10\%$ preferred stock, and $30\%$ retained earnings. Aphid$$s after$-$tax cost of debt is $4\mathrm{.}2\%,$ cost of preferred stock is $8\mathrm{.}5\%,$ and cost of retained earnings is $12\mathrm{.}1\%.$ What is the corporation$$s weighted average cost of capital? Submit your answer as a percentage and round to two decimal places $($Ex$.0\mathrm{.}00\%)$