You have a $350 public relations budget for the current year. You would like to generate publicity by publishing several ads in the local township newspaper about your store's sponsorship of community activities. The newspaper normally charges $100 per ad but will give you a 30% discount since your message is community service oriented. How many ads can you buy?

For this case, the first thing we are going to do is define the following variable:
 x = number of ads.
 We then have the following mathematical expression that models the problem:
 (100) * (1-0.3) * (x) = 375
 Where,
 100: Charges for each advertisement.
 (1-0.3): 30% discount per ad
 x: number of ads
 375: Budget available.
 Clearing x we have:
 x = (375) / ((100) * (1-0.3))
 x = 5.357142857
 Nearest whole number:
 x = 5
 Answer:
 You can buy:
 x = 5 ads.