Calculate gradient problem

Question

\begin{align*} score_k(x)&=w_kx+ b_k\forall k\in {\{1,,,k\}}\\ P(k|x)&=\frac{score_k(x_i)}{\sum_{k'}score_{k'}(x_i)}\\ E_i&=-logP(y_i|x_i)\\ \frac{\partial E_i}{\partial w_k}&=?? \end{align*} I'm trying to solve this problem. I knew that I should use chain rule. So I figured out $$\frac{\partial E_i}{\partial w_k}=\frac{\partial E_i}{\partial P_k}\frac{\partial P_k}{\partial score_k(x)}\frac{\partial score_k(x)}{\partial w_k}$$ I knew $$\frac{\partial score_k(x)}{\partial w_k}=x$$ but I can't solve the others. Thank you.