A set of lines x+y-2+λ(2x+y-3)=0 represent incident rays on an ellipse s=0 and 2x+3y-23+μ(2x+y-3)=0 represent the set of reflective rays from the  same ellipse S=0,(λ,μ∈ℝ) . If P(3,7) is a point on S=0 and if the eccentricity of  the ellipse is A-B(A,B∈N) G.C.D (A,B)=1 then A-B equals