    \begin{tikzpicture}
    \node[anchor=west,inner sep=2pt] (eq11) at (0,0) {\large{$\frac{\partial \big[ \prod\limits_{j=1}^{m} \sum\limits_{i=0}^{l} f(s_j|t_i) \big]}{\partial f(s_u|t_v)}$}};
    \node[anchor=west,inner sep=2pt] (eq12) at ([yshift=-9pt]eq11.east) {=};
    \node[anchor=west,inner sep=2pt,fill=red!20] (eq13) at ([yshift=2pt]eq12.east) {\large{$\frac{\partial \big[ \prod\limits_{j=1}^{m} \sum\limits_{i=0}^{l} f(s_j|t_i) \big]}{\partial \big[ \sum\limits_{i=0}^{l}f(s_u|t_i) \big]}$}};
    \node[anchor=west,inner sep=2pt] (eq14) at ([yshift=-1pt]eq13.east) {$\cdot$};
    \node[anchor=west,inner sep=2pt,fill=blue!20,minimum height=4em] (eq15) at ([yshift=8pt]eq14.east) {\large{$\frac{\partial \big[ \sum\limits_{i=0}^{l}f(s_u|t_i) \big]}{\partial f(s_u|t_v)}$}};
    \node[anchor=south,inner sep=1pt] (label1) at ([yshift=1pt]eq13.north) {\footnotesize{$\partial g(z)/\partial z$}};
    \node[anchor=south,inner sep=1pt] (label2) at ([yshift=1pt]eq15.north) {\footnotesize{$\partial z/\partial f$}};
    \node[anchor=north west,inner sep=2pt] (eq21) at (eq13.south west) {$\frac{\sum\limits_{j=1}^{m} \delta(s_j,s_u)}{\sum\limits_{i=0}^{l}f(s_u|t_i)} \prod\limits_{j=1}^{m} \sum\limits_{i=0}^{l} f(s_j|t_i) \cdot \sum\limits_{i=0}^{l} \delta(t_i,t_v)$};
    \node[anchor=east,inner sep=2pt] (eq20) at (eq21.west) {=};
    \end{tikzpicture}
