Combining two formulas

Hi all,

This is my first post so hopefully I get it right in one try. I have the following question:
How do I combine two Sumifs in one formula?

What I need is that Excel first calculates the total hours based on two criteria (Function A and Service A) which is 4 hours in my example
Then Excel should calculate the total hours based on two other criteria (Function B and Service B) which is 1 hour in my example
Then Excel should add these two up, so 4+1 so the cell shows the final result being 5.
(The hours are shown in a different tab)

I know that by using multiple cells it's very easy, however I would like to process this formula in one cell.

Example