1.Evaluate the following postfix expression using a stack and show the contents of the stack after execution of each operation 5,11,-,6,8,+,12,*,?.

1.Modify the class Node such that the add_node () and del_node()functions are overloaded as the operators, + and -, respectively.

Have no idea what class Node is because I'm not reading your text book and listening to your teacher. Don't just post your assignments and expect us to do your work for you. Will be glad to help you if you post the code showing you are attempting to solve the problem yourself.