It's really a bit difficult to do. It's not that no one helps you, but that discrete problems are too complicated. I painted all night last night, and now I think about it.

In a word, I can't get the number on the answer whether I use the matrix or the right compound of R relation. I feel the answer is wrong.

The above picture is the matrix operation method you said @ See if you can work out R? Haha, I can't figure it out anyway If so, please tell me if the answer is wrong. I feel dizzy.