问题如下：
Goodluck Co. has an operating profit margin of 10%, asset turnover ratio of 1.5, financial leverage multiplier of 1.6 times, and interest burden of 0.8. Company's ROE is 0.144, please calculate the company's average tax rate.
选项：
A.25%
B.75%
C.65%.
解释：
A is correct.
tax burden=0.144/(0.8 x 0.1 x 1.5x 1.6)=0.75
average tax rate =1-0.75=0.25.
- 从杜邦五分上，我不理解怎么推出来：1 - burden = tax rate
杜邦五分第一项是 NI / EBT
NI 我理解就是 EBT 里的 earning
那么 NI + tax = EBT
而 NI / EBT 是 tax burden，所以 1-tax burden= 1- NI/EBT = tax/EBT
那么问题来了，为啥 tax / EBT 就是 tax rate 了呢？ tax rate 不是应该是 tax / revenue 么？
