$\frac{\mathrm{V1}(s-\frac{x}{\mathrm{Keq1}})(2+\frac{x}{\mathrm{K1x}})^{(-1+n)}}{(1+s+\frac{x}{\mathrm{K1x}})^n+0.5(1+z)^n}$ $\frac{\mathrm{V2}x(1-\frac{y}{\mathrm{Keq2}x})}{1+x+y}$ $\frac{\mathrm{V3}y(1-\frac{z}{\mathrm{Keq3}y})}{1+y+z}$ $\frac{\mathrm{V4}(1-\frac{1}{\mathrm{Keq4}z})z}{2+z}$