2) A red black tree has 8 nodes. When we follow the tree in Preorder and Postorder order, the following results are obtained. Preorder: 20 10 Postorder: 10 40 50 30 Preorder: XYZ becomes as follows. Z 30 60 40 90 70 60 70 50 X Postorder: XYZ becomes as follows. 90 20 Z a) Draw the tree that satisfies these properties. Show which nodes are red and which are black. b) Add a node with the value 55 to this tree, show the details of the operations.