we have the expression
[tex]-27\sqrt[\square]{3}+3\sqrt[\square]{27}[/tex]Remember that
[tex]27=3^3[/tex]substitute in the original expression
[tex]-27\sqrt[\square]{3}+3\sqrt[\square]{3^3}[/tex]simplify
[tex]\begin{gathered} -27\sqrt[\square]{3}+3\cdot3\sqrt[\square]{3^{}} \\ -27\sqrt[\square]{3}+9\sqrt[\square]{3^{}} \\ -18\sqrt[\square]{3} \end{gathered}[/tex]