-1-1-1IX-2I-IX+1I+2IX-4I=2-x-x-1+2(4-x)=1-2x+8-2x=9-4x
-1IX-2I-IX+1I+2IX-4I=2-x-x-1+2(4-x)=1-2x+8-2x=9-4x