1/3 of the viewers opening rated the movie as goo and very good. 35 people rated it good and 20 people rated it very good. what is the equation to find the number of people in the audience

Since a total of 55 people rated it good/very good, we know that 1/3 of the viewers are 55 people. So we can set the equation: 1/3x=55

Now, just multiply both sides by 3 (or divide by 1/3, same thing) and get your answer!