Can someone explain how to do number 11?

First you rewrite 27 as 3^3 and then you pull the term out from under the radical , assuming real numbers 3+ square root 16 . Then you rewrite it as 3+ square root 4^2 and then you pull out terms assuming they are positive then you add 3+4 and you get 7

Ibelieve 4mn because it’s like you’re combining them