Problem is in a picture below. Please help asap, limited time.

18) Write the code to add to the end of a LinkedList where the variable first is the pointer to the first node in the list. public void add(Type obj) { } 19) Write a recursive method to find the sum of the first n even numbers. So if the method is called sumEven (5) then the method should return the sum 2+4+5+8+10 public static void sumEven(int n) { // Pre:n must be a positive integer