Install .NetFramwork 3.5 on Windows 10 using DISM

1. Insert or mount your Windows 10 disc.
2. Open a Command Prompt as Administrator.
3. Enter the following:  dism /online /enable-feature /featurename:NetFX3 /All /Source:D:\sources\sxs /LimitAccess
   NOTE:  Change “D:” after the /Source switch to the drive that contains the disc.

This should work with Windows 7, 8, and 8.1.