title: How to calculate y value on a Graph with known x value
body: <p>I have not needed to do things like this for years and was also never good at it. Below is my graph :</p>
  
  <p><a href="https://i.stack.imgur.com/Y7NoL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Y7NoL.png" alt="Graph"></a></p>
  
  <p>Looking at my artistic numbering on the graph :</p>
  
  <ol>
  <li>I have the X and Y Values : X = 7282, Y = 235</li>
  <li>I have the X and Y values : X = 8178, Y = 173</li>
  <li>I have the X but not the Y : X = 7882, Y = ?</li>
  </ol>
  
  <p>I need to calculate Y, and im sure it is pretty simple, but I cant seem to figure it out. Ive googled a lot, but all my calculations never work(i.e the new Y point is never on the line, always above or below), so im clearly missing something.</p>
  
  <p>Can anyone help with the formula of how to calculate the new Y value ?</p>
  
  <p>Thanks!</p>