Final answer:
To meet the show's expenses, the drama club must sell at least 56 adult tickets.
Step-by-step explanation:
To determine the number of adult tickets the drama club must sell in order to meet the show's expenses, we need to find the remaining amount that needs to be raised after selling the student tickets. We know that the drama club must make no less than $790 from ticket sales, and 69 student tickets have been sold at $5 each, which amounts to $345. So, the drama club needs to raise $790 - $345 = $445 from adult ticket sales.
Now, let's consider the cost of each adult ticket, which is $8. To find the number of adult tickets that need to be sold, we divide the total amount that needs to be raised by the cost of each adult ticket: $445 ÷ $8 = 55.625.
Since we cannot sell a fraction of a ticket, we need to round up to the nearest whole number. Therefore, the drama club must sell at least 56 adult tickets in order to meet the show's expenses.