Answer

Six parameters are estimatable: d_V V_b, d_V/d_E, K, $\dot{k}_M$, g and $d_V^{1/3} \dot{v}$, or functions of these (compound) parameters. Knowledge about the values of X can be used in this case to obtain K and f; this is because the relationship between W_b = (d_V + f d_E) V_b and X has three parameters, K, d_V V_b and d_E V_b, and we have three observations.