title: Add normal distribution curve to histogram R
body: <p>I'm trying to overlay a normal distribution curve onto a histogram in R. I know it's a question that's been asked before, but I'm having trouble getting the solutions to work for me. </p>
  
  <p>This is my code: </p>
  
  <pre><code>hist(input_data$"X109_scalesraw_23", freq = TRUE, breaks = 30, 
       col = "cadetblue", xlim = c(0,30), ylim = c(0,150), 
       main = "023", xlab = "score")
  </code></pre>