NPV means sum of all aggregate discounted cash flow (including initial investment).

Here intial investment is required $ 100 million, which will funded in 60% owners capital and 40% debt capital at 5% interest cost.

Revenue generated $ 20 million for 10 years

Required rate of return on equity = 10%

Tax rate is 30%

So,

Owners capital (60% * $ 100 million) = $ 60 million

Debt capital at 5% = $ 40 million

Interest cost per year = $ 2 million

Cash flow every year = revenue - interest cost - Tax

$ 20 million - $ 2 million - $5.4 million (30% * $ 18 million) = $ 12.6 million

So every year upto 10 year a cash flow of $ 12.6 million

cost of capital = [10% (Required rate of return on equity) * $ 60 million + 5% (debt cost) * $ 40 million] / $ 100 million

= 8%

So discounting rate or cost of capital is 8%.

NPV =

I have used excel formula to calculate NPV.

PLEASE SEE THE ATTCHED FILE.