If  $e_1\mathrm{and}{e}_2$ are the eccentricities of the ellipse $\frac{x^2}{18}+\frac{y^2}{4}=1$  and the hyperbola  $\frac{x^2}{9}-\frac{y^2}{4}=1$ respectively and $(e_1,e_2)$    is a point on the ellipse  $15x^2+3y^2=k$ then ‘k’ is