How do u find the initial value on a graph

What you would need to do is:

1) Determine the rate of change

2) Find the function

(initial value) of x and y values.

First, you have to find the axis of symmetry and vertex. Next, make a function to model a linear relationship between the two quantities. Finally, find the rate of change and initial value of the function from a description of a relationship or from 2 (x, y) values, including reading these from graph or a table.