please help with explanation

3. Use the operations push, pop, top, and isEmpty to construct pse operations that do each of the following: Empty to construct pseudocode a) Set num to the third element from the top of the stack, lea its top three elements. ick, leaving the stack without b) Set num to the third element from unchanged. the top of the stack, k, leaving the stack Focus on Data Structures Page 129 + num to the nth element from the the stack, leaving ven an integer n, set num to the nt ack without its top n elements. c) Given an the stack with ent from the top of the stack, leaving integer n, set num to the nth element fro d) Given an integer the stack unchanged. om element of the stack, leaving the start leaving the stack empty. e) Set num to the bottom eleme the stack, leaving the stack unchanged. um to the bottom element of the stack, le Set num to the botte to the nth element from the bottom of the ottom of the stack leaving the stack g) Set num to the nth unchanged