task main ()
{
  while (true){
    int Left = SensorValue(EyeLeft);                  
    int Right = SensorValue (EyeRight);

    //black = 12;
    //white   = 3;


    if (SensorValue(EyeLeft) == Left && SensorValue(EyeRight) == Right){      // both sensors see white, the robot must go straight
      motor[MotorLeft] = 35;      
      motor[MotorRight] = 35;     }

    if (SensorValue(EyeLeft) > Left ){                  // left sensor sees black, so the robot must go to the right         
      motor[MotorLeft] = -20;
      motor[MotorRight] = 50;      }

    if (SensorValue(EyeRight) > Right){                  // right sensor sees black, so the robot must go to the left
      motor[MotorLeft] = 50;
      motor[MotorRight] = -20;     }
              }
}

task main ()
{
  int LeftThreshold = 8;      // feel free to change this based on your own calculations!
  int RightThreshold = 8;     // and this!  (I used the values you have below)
   
  //black = 12;
  //white   = 3;
 
  while (true)
  {
    // LEFT = light, RIGHT = light:
    if(SensorValue(EyeLeft) < LeftThreshold  &&  SensorValue(EyeRight) < RightThreshold)
    {   // go FORWARD
      motor[MotorLeft] = 35;
      motor[MotorRight] = 35;
    }
    // LEFT = light, RIGHT = dark:
    else if(SensorValue(EyeLeft) < LeftThreshold  &&  SensorValue(EyeRight) > RightThreshold)
    {   // go LEFT         
      motor[MotorLeft] = -20;
      motor[MotorRight] = 50;     
    }
   
    // LEFT = dark, RIGHT = light:
    else if(SensorValue(EyeLeft) > LeftThreshold  &&  SensorValue(EyeRight) < RightThreshold)
    {   // go RIGHT
      motor[MotorLeft] = 50;
      motor[MotorRight] = -20;     
    }

    // LEFT = dark, RIGHT = dark:
    else
    {   // do what you want here, I'm just putting a stop:
      motor[MotorLeft] = 0;     
      motor[MotorRight] = 0;     
    }
  }
}