Answer:$52
Step-by-step explanation: I would first set up an equation. 9a=18 (a means attendees). Then, I would divide both sides by 9 to isolate the a. I would get a=2. So now I know that 1 attendee costs 2 dollars. If I want to find the cost for 26 attendees, all I would have to do is multiply both sides of the equation a=2 by 26. I would get 26a=52. So, 26 attendees cost $52. I hope this helps you out!