My suggestion is to look on google, there are plenty of answers and I think it will explain better than me.
Answer:
47 very easy
Step-by-step explanation:
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The equation of the vertical parabola in vertex form is written as

Where (h, k) are the coordinates of the vertex and p is the focal distance.
The directrix of a parabola is a line which every point of the parabola is equally distant to this line and the focus of the parabola. The vertex is located between the focus and the directrix, therefore, the distance between the y-coordinate of the vertex and the directrix represents the focal distance.

Using this value for p and (3, 1) as the vertex, we have our equation
Answer:
The 70 represents the number of people waiting to by tickets at the exactly moment when the ticket booth is opened.
Step-by-step explanation:
The 70 represents the number of people waiting to by tickets at the exactly moment when the ticket booth is opened.
You can see this by setting the x value to 0, it is, in the precise moment when the booth opened (as x cant be negative, because there is no negative time, you could also think of 70 as the number of people waiting before the booth opens).