Ayratonia, a working project manager and promising musician, wants to purchase a new guitar and case for $$9700.$ When they learned of this opportunity, the grandparents provided a gift of $$2400.$ She adds the $$2400$ to a current investment portfolio yielding an average of $8\mathrm{.}13\%$ per year $($first dividend is received one year after the initial purchase$)$ and borrows the entire amount of the case at a rate of $5\mathrm{.}78\%$ per year. Determine the WACC $\%$ per year $($Round the final answer to two decimal places.$)$