#define PINS 3

const byte rgb_pins[PINS] = {9, 10, 11}, potentionmeters_pins[PINS] = {A0, A1, A2};

void setup() 
{
  for(byte i = 9; i <= 11; i++)
  {
    pinMode(i, OUTPUT);
  }
}

void loop()
{
  for(byte i = 0; i < PINS; i++)  
    analogWrite(rgb_pins[i], 255 - map(analogRead(potentionmeters_pins[i]), 0, 1023, 0, 255));
}