5. What must be the first line of a method definition, and what information does it contain? 6. If a method doesn't return a value, what type should it be declared? 7. What is the significance of empty parenthesis in a method invocation? 8. How many values can be returned from a method? 9. What is the value of x and y after executing the following program? public class MysteryNums { public static void main(String[] args) { int x = 15; sentence(x, 4); int y = x - 5; sentence(y,x); System.out.println(x +"&" + y); } public static void sentence(int num1, int num2) { num1 = num 1 + num2; } }