Rafael wants to spend $250 for his party. According to the pricing structure:
- $100 for the first 10 people
- $150 for more than 10 and up to 20 people
- $200 for more than 20 and up to 30 people
- $250 for more than 30 and up to 40 people
- $275 for more than 40 and up to 50 people
Since Rafael wants to spend $250, the only applicable pricing tier is the one for more than 30 up to 40 people.
Thus, if he spends $250, he can invite anywhere from 31 to 40 people.
So the correct response is: 30 < x ≤ 40.