Can I multiply a static and a non static variables, like this: 

```
public class C {  
    protected int c;  
    private static int s;  
    public int ma() { return this.c*this.s; }  
}  

```

Or: 

```
public class B{  
    protected int x;  
    private static int y;  
    public static int ms() { return x + y; }  
}   

```

The second code is not working and I am wondering is it because it's expecting static?