Answer 1

/*The problem is you haven't created any object of the class "hello" and you are using it's method in main class.

It's a rule of OOPs that
if you want to use a method of class in another class then you have to create an object of the class that you want to use.

Here his solution to your problem:
*/

class hello
{
public void sam(int a,int b)
{
int sum=a+b;
System.out.println("sum="+sum);
}
}
class Demo
{
public static void main(String args[])throws Exception
{
hello a = new hello();
a.sam(90,30);
}
}

/*
I have just created an object named "a" to use the method sam().

To use method sam() just call it by the line

a.same(90,30);

If you got any doubt you can ask.

if you want to test it just copy this comment and run it with java compiler

Hope this will help😄
*/

Answer 2

or

//public void sam(int a,int b)
static public void sam(int a,int b)

//sam(90,30);
hello.sam(90,30);

Answer 3

The problem in this is u dont know java😁