Answer:
The attendance on tuesday, october 4, is of 144 people.
Explanation:
The attendance after t days is given by the following equation:

In which A(0) is the attendance on the first day and r is the daily decrease rate.
Premieres on saturday, october 1, and 420 people attend.
This means that

Attendance then decreases by 30% each day.
This means that

So



Find the attendance on tuesday , october 4
This is 4-1 = 3 days after saturday. So this is A(3).

The attendance on tuesday, october 4, is of 144 people.