since you have a multiplicity of 2at x=3 this gives you a factor of (x-3)^2
The single multiplicities give you factors of c and (x+3) so equation is
y =a(x-3)^2(x)(x+3). Use the point (5,112) to solve for a
a(5-3)^2(5)(5+3)=112
a(4)(5)(8)=112
a=7/10 or .7 so final equation is
y=.7(x-3)^2(x)(x+3)