Which groups in american society might have opposed progressive reform? explain.

In the late 19th and early 20th century, it was mainly big businesses and corporations that opposed Progressive reform in the United States, since the main purpose of these reforms was to regulate business and eliminate corruption. 

Use the formula: (n-2)×180, where n is the number of sides(18-2)×180= 28800, now this is the full exterior angle of 18-gon so you divide it by 18.28800÷18=160