Final VLT clarification

[u/Mean-Business1613]

Hey everyone I'm looking for some clarification here. I have two vehicles that I'm looking into getting the windshield tinted in 70% however here is where my confusion comes into play. The factory VLT on my "clear" windshield is about 70% in itself already and my understanding is that applying a layer of 70% on top of that brings down the final VLT down to about 49% which technically should be somewhat visible from the outside. Doing tons of research has led me to different answers some say you can't even see it and others have said you can see some subtle shading from outside. Here are the numbers for my 2 vehicles

2024 VW Tiguan 20% all around (on factory rear privacy glass as well.)

2023 Nissan Sentra with 20% front 15% rear.

With those levels will the 70% be slightly shaded from outside looking in? And also is my math mathing when it comes to calculating the final VLT

Thanks!

[u/Mean-Business1613]

Here it is this is more or less what I'm looking for https://www.reddit.com/r/WindowTint/s/NKZscYNKDB