Answer:
Let's call the total number of chairs in the theater "x". Since Alison's seat is 3rd from the front, there are 2 chairs in front of her. Similarly, since her seat is 18th from the back, there are 17 chairs behind her. Therefore, the number of chairs between the 2 chairs that Alison and Naida are sitting on is: x - (2 + 17) = x - 19 Now, if Naida can see 8 chairs to her left and 11 chairs to her right, that means there are 8 + 1 + 11 = 20 chairs between her and Alison. So we can set up an equation: (x - 19) - 20 = Alison's seat number Simplifying this equation: x - 39 = Alison's seat number We