c= total cost of hosting a birthday party ata skating ring
p= number of people atending
The relationship between the cost and the guests number is:
c = 5p + 215
Her parents are willing to spend $330, this is a value of c, replace it in the formula:
330= 5p + 215
Now you have an equation with only one unknown p
Pass the term without the variable to the other side and you have that:
5p=330-215
5p=115
Then divide it by 5 to reach the value of guests she will be able to invite:
p= 115/5
p=23
23 persons will be able to attend the party.
