I have the following question

[![enter image description here][1]][1]


And I have the formula for finding the pressure difference which is as follows:  
$$P(below) = P(above) + ρgh  $$
And since they provide the information that it is vacuum, then Patm > Pabs. 

Here is the solution:  
[![enter image description here][2]][2]


I don't really understand why it is minus ρgh and I'm confused how to use the fact that it is vacuum. Also, what can we usually consider P(below) and P(above)?

  [1]: https://i.sstatic.net/UOq4C.png
  [2]: https://i.sstatic.net/YwL5d.png