The formula c = 5p + 215 relates c, the total cost in dollars of hosting a birthday party at a skating rink, to p, the number of people attending, if allie's parents are willing to spend $300 for a party how many people can attend?

Given:
c = cost
p = people
Spent $300

Formula: c=5p+215

Solving for how many people (p)

C=5P+215
(300)=5P+215               (Subtract 215 on both sides)
85=5P                           (Divide by 5 on both sides)
17=P

The answer is 17. 17 people can afford to host a birthday party.