a$)(35$ pts$)$ Build an AVL tree after successively inserting the keys: $91,33,64,75,27,13,73,60,89,87,20,9,12,25,26,79,74,5.$ Show and explain every iteration.

b$)(15$ pts$)$ Traverse the tree you build in$-$order, pre$-$order, and post$-$order.