title: Predict y value for a given x in R
body: <p>I have a linear model:</p>
  
  <pre><code>mod=lm(weight~age, data=f2)
  </code></pre>
  
  <p>I would like to input an age value and have returned the corresponding weight from this model. This is probably simple, but I have not found a simple way to do this.</p>