What is the cost of a 7-line ad if it charges 14.50 for every three lines of a ad?

You have 7 lines and per 3 lines you're charged $14.50.  7 divided by 3 is 2.33333333. 14.50 X 2 = $29. Now you solve for the unit price ( the cost per one line and multiply that by 2 ) So the unit price is about $4.83. $4.83 x 2.33333 = $11.27. The total cost would be about $40.27. 

I hope this helps :)