Start with an AVL tree that has a single node containing the key 15. Consecutively insert the following keys to the tree. At each step, insert the key, draw the new tree, and check to see if the tree still has the AVL property. If it doesnt, fix it using single or double rotation, and draw the new tree, and explain which rotation you used.

Keys to enter: 10, 5, 20, 25, 30, 35, 50, 45, 40