You can put this solution on YOUR website!
If I had to make a guess, the line is probably the directrix of the parabola. I'm not entirely sure. The notation of y = 4 - 1/(1 * 151) seems particularly odd.
Edit: After using GeoGebra, the app is telling me the directrix is exactly y = 3.95 which is not the value of 4 - 1/(1 * 151) = 3.9933774834437 approximately
So I'm not sure what y = 4 - 1/(1 * 151) could be referring to.