I found the instructions pretty confusing because you're not actually moving anything. You're combining the first selected row/column with the second selected row/column and replacing the second with the result of the combination.

I agree, to this point, my expectation was that it would animate for me the combination and updated result after my choice. I had to fill that gap and it confused me at first.

Yep, I see what you're saying; let me try to clarify that part!