title: I want to subtract the values ​in datagridview3 row 0 by their total mean, and display the results in datagridview4. but the result doesnt match
body: <p>please to help me i am still newbie,
  this is my code, and i can't solve it.
  I want to subtract the values ​​in datagridview3 row 0 by their total mean, and display the results in datagridview4. but the result doesnt match.</p>
  <p>the code
  <a href="https://i.stack.imgur.com/zFhAT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zFhAT.png" alt="enter image description here" /></a></p>