By 1920, most inventors worked for

How did the voting rights act and the 15th amendment combine to improve individual rights for african americans

The rise of advertising in the 1920s. i am good with seeing how advertisements shape the roaring twenties and how it developed a new way of life through modern days. but i am not sure what the details of advertising in the 1920s were. if possible can you send me links (preferrably credential links) to sources that maybe show like the first company to start advertising through the radio, how advertising benefits (statistics graphs), etc.

Which of these constitutional amendments made all people born or naturalized in the united states into citizens of the united states ?