In this talk, we consider a Hessian equation with its structure as a combination of elementary symmetric functions on closed Kahler manifolds. We provide a sufficient and necessary condition for the solvability of this equation, which generalizes the results of Hessian equation and Hessian quotient equation. The key to our argument is a clever use of the special properties of the Hessian quotient operator $\frac{\sigma_k}{\sigma_{k-1}}$.