This will be a parabola sitting on its side opening to the right. Draw a general sketch of the parabola with the information given to see this so equation is x= a(y-k)^2 +h
hand k are the coordinates of the vertex and are both zero. Solving for a we have
48=a(_12)^2 + 0
48= 144a a=1/3 so equation is
x=(1/3)y^2