v$.$ What is the weighted average cost of capital $($WACC$)$ after taxes for Aleoa Ltd$?$

WACC$=25\%**9\mathrm{.}09\%+25\%**6\mathrm{.}14\%**(1-0\mathrm{.}35)+50\%**10\mathrm{.}57\%=8\mathrm{.}56\%$

Explain the answer with the formula