f(x)=x/x-3 and g(x)=1/2x-1 show that gf(x)=1-(6/x+3)?

Well,

f(x)=x/(x-3) and g(x)=1/(2x-1)
then
(gof)(x) = g(f(x))
= g( x/(x-3) )
= 1/(2x/(x-3) - 1)
= 1/[( 2x - x + 3)/(x-3) ]
= (x-3)/(x+3)
= (x + 3 - 3 - 3)/(x+3)
= (x+3)/(x+3) - 6/(x+3)
= 1 - 6/(x+3)

qed

hope it' ll help !!

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Question is unclear.
Is it meant to be x / (x - 3) ????
What then ?
1 / (2x - 1) or 1/(2x) - 1 or (1/2) x - 1 ????

Brackets must be used to make questions absolutely clear.