Let output of summer is K (s). Then

K(s) =	C(s)
	G₂ G₃

∴	C(s)	= G₁		R(s) -	C(s)H₁		- C(s)H₂
	G₂ G₃				G₃

⇒ C(s) [1 + H₁ G₁ G₂ + H₂ G₂ G₃ ] = G₁ G₂ G₃ R (s)

⇒	C(s)	=	G₁ G₂ G₃
	R(s)		1 + H₂G₂G₃ + H₁G₁G₂

For block diagram shown in the figure,	C(s)	is given by
	R(s)