Question 1169506
Imagining vertex (0,0) and a minimum point, symmetry axis x=0.
then  parabola also will have  (-21,15) and (21,15).


{{{75y/7=x^2}}}


Focus, if some p units above the vertex,
{{{4p=75/7}}}

{{{p=75/28}}}


{{{p=2.68}}} centimeters