* The cost of the prom is $6,160
* Tickets are $40 for a single attendee or $70 for a couple (2 people)
* Let's break this down:
* If x people attend as singles, they will buy x tickets at $40 each, so they contribute x * $40 to the revenue
* If x people attend as couples, there are 2x people total who buy x tickets at $70 each, so they contribute x * $70 to the revenue
* Since an equal number attend as singles and couples, x must be the same in both cases
* We need:
* x * $40 (revenue from singles) + x * $70 (revenue from couples) >= $6,160 (cost of prom)
* x * $40 + x * $70 >= $6,160
* x * ($40 + $70) >= $6,160
* x * $110 >= $6,160
* x >= 6,160/110
* x >= 56
* Therefore, the minimum number of people who must attend is 56.
The answer is A.