i don’t understand how to do this kind of problem (#3)

30 -60 -90 theorem helps us to relate the sides and angles of a right triangle as follows
since
2x=12
then
[tex]2x=12[/tex][tex]x=\frac{12}{2}[/tex][tex]x=6[/tex][tex]y=x\sqrt{3}[/tex][tex]y=6\sqrt{3}[/tex]