Answer:
1,500 people
Step-by-step explanation:
Remember that

Convert ft to in

<em>Divide the length of a row by the space occupied by one person</em>

<em>Multiply by the number of rows to determine the total people that can fit into the stands</em>

Let's focus on the given equation. The C represents the cost, while the x must be the number of tacos, which is what we're solving for. Since we're given the boundary that C must be 300, then the solution would be:
300 = x² - 40x + 610
x² - 40x + 310 = 0
Apply the quadratic formula where a = 1, b = -40 and c = 310. The roots of x are:
x = 29.49≈30
x = 10.51≈11
<em>Thus, she needs to sell either 30 or 11 tacos.</em>
Answer: We should add the constant 81 to the expression to have a perfect square trinomial.
The perfect square trinomial that would be formed would result from (x + 9)^2.
We can use foil to prove it.
(x + 9)(x + 9)
x^2 + 9x + 9x + 81
x^2 + 18x + 81
81 is the value that must go with 18x in the middle to form the perfect square trinomial.