\documentclass[11pt,a4paper]{article} \begin{document} \[\bar n^*_j(s)=\frac{\left\{s\sum^k_{i=1}n_i(0)p^*_{i,k+1}(s)+M^*(s)\right\}\sum^k_{i=1}p_(0i)p^*{ij}(s)}{1-s\sum^k_{i=1}p_{0i}p^*_{i,k+1}(s)}+\sum^k_{i=1}n_i(0)p^*_{ij}(s),\quad (j=1,2,\dots,k).\] \end{document}