To determine viable solutions for the inequality \( 7x + 4y \geq 400 \), where \( x \) represents the number of adult tickets sold and \( y \) represents the number of children's tickets sold, we need to consider the nature of the variables involved.
- Adult tickets and children's tickets are not negative: You cannot sell a negative number of tickets, and you cannot sell a fraction of a ticket in this context. Therefore, both \( x \) and \( y \) must be non-negative whole numbers.
Given these considerations, the correct response would be:
A viable solution will have only positive whole numbers.