hello dr.mo

I think that my problem is simple,

here is my code

import controlP5.*;
ControlP5 controlP5;

int a = 30;
int b = 255;

void setup() {
  size(170,150);
  controlP5 = new ControlP5(this);
  controlP5.addSlider("a",0, 255, 5, 50, 150, 15).linebreak();
  controlP5.addSlider("b",0, 255, 5, 100, 150, 15).linebreak(); 
}
void draw() {
   background(a,b,255); 

// I try to decrease "b" acordding to "a" when I slider move up, some kind of inverting to "a" to "b"

if (a > 30 ){
      b =  a/ 2;
} else {
  b=b;
 }

}  
///////////////////////////////////////////////////////////////////////////////////

think about 2 pool.
one is "a"
other is "b"
ones is full of %30
when I'm filling the "a"
"b" is decreasing according to "a" (slider value)
I cant solve the problem

all problem is about that.
 

There is no program apparently :)
I'm working on writing a program.

I try to combine with some ideas, variables with some of functions.

I'm collage student in Turkey. Im at home for a while. When I at home, I want to studying some basic of programing languages. I choose processing because its basic to learn some of function name for example size(), text() fill() and Processing is very enjoyeble. I found lots of tutorial on web. On the other hands if I can't the solve the basics of invertion problem I think that, writting a program really hard to me.

What do you suggest to me ?
Can you explain what are you doing if you can't solve your problem.?    

Thank you very much

Merakli