title: geom_smooth and geom_line regression line creation
body: <p>I am getting two outputs for following steps in R:</p>
  
  <ol>
  <li><p><code>ggplot(mario_kart, aes(y = totalPr, x = duration, color=cond)) + geom_point() + geom_smooth(method = "lm", se = 0)</code></p></li>
  <li><p><code>ggplot(mario_kart, aes(y = totalPr, x = duration, color=cond)) + geom_point() + geom_line(data=broom::augment(lm(totalPr~duration+cond,data=mario_kart)), aes(y=(.fitted)))</code></p></li>
  </ol>
  
  <p>I want to understand how data is getting manipulated and exactly how can I know whether I am using the correct method in ggplot.</p>