长期债券成本=10%*(1-25%)/(1-2%)=7.65%优先股成本率=12%/(1-3%)=12.37%普通股成本率=12%/(1-5%)+4%=16.63%加权平均，权重分别为40%、16%、44%加权平均资金成本率=7.65%*40%+12.37%*16%+16.63%*44%=12.36%
