+36 Problem:
Find AC.
[asy] size(300); pair A,B,C,O; A=origin; B=6*sqrt(3)*dir(150); C=(5,0);draw(A--B--C--cycle); dot("$A$",A,SW); dot("$B$",B,NW); dot("$C$",C,SE); label("$150^\circ$",A,dir(75)); label("$9$",A--B,SW); label("$7\sqrt{3}$",C--B,NE); [/asy]
thx for any helpers!
