//4-3 varying variables, circle moves across the screen & back

int circleX= 0;
int circleY= 100;
int speed= 5;

void setup() {
  size(200,200);
}

void draw() {
  background (255);
  stroke(0);
  fill(175);
  ellipse(circleX, circleY, 50, 50);
  circleX = circleX +speed;
      if ((circleX > width) || (circleX <0)){
    speed= speed *-1;
 }
}