When calculating the sound transmission loss how do I weight the window and the wall?

Wall A has a sound transmission loss (TL) of 60 in the opaque portion and five percent of the surface of the wall is covered by window (TL of 25).

Wall B has a sound transmission loss of 40 for the whole assembly (there is no window in Wall B)

Which will do a better job keeping passing bus noise out of the apartment, Wall A or Wall B

Given

Click here to watch my video answer. --Michael Ermann, Amber Book creator