Using the equation for the line of the best fit, what is a good approximation for x when f (x) is equal to 30

Then the vertex is at (h, k) = (2, - 3) and the value of p is - 3. Since y is squared and p is negative, then this is a sideways parabola that opens to the left. This puts the focus 3 units to the left of the vertex.

vertex: (2, - 3); focus: (-1, - 3)