41 installing NET framework 3.5 on windows 10 Offline using DISM the simple way
Mount your ISO first and then copy this command to an elevated command prompt:
Dism /online /enable-feature /featurename:NetFX3 /All /Source:D:\sources\sxs /LimitAccess
Then change the drive letter accordingly.
/ @ramdisktesting5068 for more.