Ans.

20	-2	4	=	1	0	0	*	U11	U12	U13
-1	-10	1		121	1	0		0	U22	U23
2	3	20		131	132	1		0	0	U33
			=	U11			U12		U13
				L21U11 l21U12+U22 l21					U13+U23
				L31U11 l31U12+l32U22 l31U13+l32U23+U33

Comparing on both sides, we get

U11=20
U12=-2
U13=4
L21U11=-1
L21 = -1/20
L21U12+U22=-10
U22= -101/10
L21U13+U23=1
U23=6/5
L31U11=2
L31=1/10
L31U12+L32U22=3
L32= -32/101

L31U13+L32U23+U33=20
U33=2018/101

L =	1 -1/20 1/10	0 1 -32/101 1	0 0
	20	2	4

U =	0	-101/10 6/5
	0	0	2018/101

Ly=b
L	*	(Y1)	=	(8)
		(Y1)		(-3)
		(Y1)		(7)

By solving the above eqn, we get

Y1=8
Y2=-13/5
Y3=5.38


Now Ux = y

U	*	X1	8
		X2	-13/5
		X3	5.38

By solving the above eqn, we get


X1 =0.4247 (approx)
X2=0.289386138(approx)
X3=0.269066402(approx)