title: Substract last cell in row from first cell with number
body: <p>I have the following Excel sheet
  <img src="https://i.stack.imgur.com/3fbc7.png" alt="enter image description here"></p>
  
  <p>In column J i need the final difference between the first cell in the row and the last cell (with a number).</p>
  
  <p>Numbers can appear from column C until column I. Numbers do not always start in column C and do not always end in column I, but there are never empty cells in between. </p>
  
  <p>Basically i need to subtract the value in the first cell with a number from the last cell with a number. The last value in the range from C-I minus the first value in that range with the result being displayed in J.
  I filled in column J manually for now, however I would like to do it with formula.</p>