The function is included circled in red... what I am trying to figure out is how to extrapolate a data point using an X-value... like let's say I want to determine where on the line the point would be if X = 7.2. How would I calculate Y using this information?

Explanations on the level of "See Jack Run" are greatly appreciated, I'm at the point where I don't know enough to know what I don't know. Any help much appreciated....