Mark ordere wome balloons for a party that she is having. the balloons cost $4.50 each and there is a service fee of $12.the total cost is $79.50. write an equation represents this situation, then solve doe how many balloons were purchased for the party.

A general equation to use for this situation is y = mx + b.

For this question, we can assume that y is total cost, m is cost per balloon, x is the amount of balloons, and b as the service fee; so we can set the equation up:

y = (4.50)x + 12

And we can further plug in the total cost to find the number of balloons purchased for the party:

79.50 = (4.50)x + 12

Now we can solve for x (number of balloons):

67.50 = (4.50)x

x = 15

The total number of balloons purchased for the party is 15.