老师，为什么这里计算interest时不乘以（1-40%）呢？

问题如下：

Based on the following information, determine whether Vertically Integrated Manufacturing (VIM) earned any residual income for its shareholders:

• VIM had total assets of $3,000,000, financed with twice as much debt capital as equity capital.

• VIM’s pretax cost of debt is 6 percent and cost of equity capital is 10 percent.

• VIM had EBIT of $300,000 and was taxed at a rate of 40 percent.

Calculate residual income by using the method based on deducting an equity charge.

选项：

A.

$8,000

B.

$8,200

C.

$8,400

解释：

Yes, VIM earned a positive residual income of $8,000.

Equity charge = Equity capital × Required return on equity

= (1/3) ($3,000,000) × 0.10= $1,000,000 × 0.10 = $100,000

Residual income = Net income -Equity charge= $108,000 -$100,000 = $8,000