Expression property consisting of: Layer name + "/" + Parent ID name. How to do it?

[TKnudsen]

I am trying to make a property with and expression, so that elements automatically looks like this:
"Layer name" + "Parent ID" divided by a "/" symbol.

For example:

"YVH-01/A" - Where 'YVH-01' is the name of the layer and 'A' is the Parent ID.

Can anyone help with an expression for this?

Thanks 🙂