Can u help me to understand and answer each question (a,b,c and d)

Question The model (P) below has been solved by the SP method according to a selection criterion of the separation variable. Two partial enumeration trees, in which some information (node numbers, ...) has been deleted, are reproduced below. MaxZ=5x1+8x2 under the constraints x1+x26,5x1+9x212x10,x20x1etx2integers. For each enumeration tree: a) Calculate the optimal values (zh) from the information provided in the trees in the figures below (if applicable). b) Build the sequence of separations, stating explicitly, which nodes are discarded, which remain in a queue. c) If applicable, describe the next separation: from which node (Ph) does the separation take place? what constraints are attached to (Ph) on each of the branches emerging from (Ph) ? d) Write explicitly the linear model associated with this node (Ph) at From which the next separation will take place. Arbre d'numration 1 Arbre d'numration 2 \begin{tabular}{|c|} \hline P \\ \hline Non ralisable \\ \hline \end{tabular}