Merging two cells and separating data with symbol

Hi all!

I've a file (structure is always the same) with data that I need to merge and separate with "+".
More precisely, in "Tutor" sheet you find columns with "Tutor 1", "Tutor 2", etc.
For each tutor, for each day, there are two cells (both with/without text or only one of them).
I need that always (also if they're empty) the 2 cells (for each day) are merged and, if both cells contain text, data must be separated by "+").

In "Desidered" sheet you can find an example of what I ask.

Please, can someone help me?

Note 1: "Tutor 1, 2, etc" will be replaced by real name.
Note 2: AC and AD columns can be deleted.