How are lease epenses considered in cash-flow calculation?

Baffles me that this never has been clearly explained in tutorials (wil tell you at the end what BIWS say). 

But my main question is: when I account for a capital lease I will split the lease in hypothetical principal repayments and debt interest payments. On top of that I will depreciate the lease asset.

How do I derive real cash flows from this hypothetical interest/principal repayment figures?

Let me make an example: 

Revenue: 100 

Lease Asset D&A: 15 

Lease principal repayment: 12 

Interest: 8 

"Real" Lease Expense thus 20 

Taxes: 40% 

No other cost or expenses 

On my income statement I have Revenue 100 - 15 (D&A) - 8 (Interest) = 77 (Pre Tax Profit) * (1-40%) = 46.2 Net income 

Now what are my "real" cash flows?

I certainly have two pay two things:

a) The lease expense of 20 

b) The tax of 30.8 (77 *40%) 

Which all things being equal would lead to cash increase of 49.2

But how would I arrive at that figure when calculating my operating cash flow and UFCF? 

1) Operating cash flow: 

Net Income: 46.2  + 15 D&A = 61.2 (Wrong) 

2) UFCF - the way BIWS tells it, he says don't add back lease D&A

85 (EBIT) *(1-40%) = 51 + 0 Lease D&A 

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So what is the correct whay of doing this? 1) certainly arrives at wrong operating cash flows but is at least 2) somewhat good to use for valuation purposes?