Hi, I'm trying to solve this problem but I'm having a lot of trouble since if I treat the bracketed part as 1 entity as I assumed I was supposed to, then I get a du value of which I can't figure out how to convert back to (i realize that it is likely very simple though).

If I don't treat the bracketed part as 1 entity however, then I am unsure as to how to include the part in my solution.

Any help wold be appreciated.