Infix expressions are usually converted into a postfix expression before being evaluated. Usually, stack data structure is used to perform the conversion (a) Convert the following infix expression to postfix expression using stack and list the content of stack when D is read. ((A+B)* C-D)*E on (b) If the values of A, B, C and D are 2, 6, 3 and 1, respectively, manually calculate the value of the following postfix expressions: 1. ABC-D ABC + D