The overall transfer function of the system in the given

Y₁ = U + X₂H
Y₂ = U + X₁H
and X₁ = GY₁ = GU + GX₂H
X₂ = GY₂ = GU + GX₁H
⇒ Y = X₁ + X₂ = 2 GU + GH (X₁ + X₂)
= 2 GU + GHY

⇒ Y =	2GU
	1 - GH

⇒	Y	=	2G
	U		1 - GH