1/2{1/2[1/2(1/2x-3)-3]-3}-3=0,1/2{1/2[1/2(1/2x-3)-3]-3}=31/2[1/2(1/2x-3)-3]-3=61/2[1/2(1/2x-3)-3]=91/2(1/2x-3)-3=181/2(1/2x-3)=211/2x-3=421/2x=45x=90
90
