Let's analyze the problem:

• The auditorium has many seats, and only 1/6 of them have been filled.
• Of the remaining open seats, 20% have been reserved for special guests.
• We are asked to find what portion of the entire auditorium is still available for seating.

Step 1: Seats that are filled

The fraction of seats that are filled is given as $\frac{1}{6}$. Therefore, the open seats are the remaining fraction of the auditorium: $1 - \frac{1}{6} = \frac{6}{6} - \frac{1}{6} = \frac{5}{6}$ So, $\frac{5}{6}$ of the seats are open.

Step 2: Seats reserved for special guests

Of the open seats, 20% are reserved for special guests. To find out how many of the open seats are reserved, we calculate 20% of $\frac{5}{6}$: $\text{Reserved seats} = 0.20 \times \frac{5}{6} = \frac{20}{100} \times \frac{5}{6} = \frac{1}{5} \times \frac{5}{6} = \frac{1}{6}$

Step 3: Remaining seats available for seating

The portion of the auditorium available for general seating is the open seats minus the reserved seats: [ \text{Available for seating} = \frac{5}{6} - \frac{1}{6} = \frac{4}{6