what are the economic benefits of union membership to employers, and to what extent can these benefits be increased before employers face problems?

In a 3-5 page paper discuss what are the economic benefits of union membership to employers, and to what extent can these benefits be increased before employers face problems?

APA format for reference

1st page cover page 

A reference page. And at least 3 page body of paper

This is for a Fair Practices--Labor Relations in the Public Sector class.