Answer: At least 713 paintballs
Explanation:
Based on the information that has been given in the question, the inequality that'll be used to solve the question will be:
18+0.08B≥75
0.08B≥75-18
0.08B≥57
B≥57/0.08
B≥712.5
Carolina needs to buy at least 713 paintballs along with the entrance fee to get the promotion.