Assumption: the given expression is meant to be:
(x/3 -2)/(3/x^2+4/x)x3−23x2+4x
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color(blue)("Consider the numerator")Consider the numerator
x/3-2 -> x/3-6/3 color(blue)(= (x-6)/3)x3−2→x3−63=x−63
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color(blue)("Consider the denominator")Consider the denominator
3/x^2+4/x -> (3x+4x^2)/x^23x2+4x→3x+4x2x2
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color(blue)("Putting it all together")Putting it all together
(x-6)/3 -: (3x+4x^2)/x^2x−63÷3x+4x2x2
(x-6)/3xxx^2/(3x+4x^2) " "=" "(x^3-6x^2)/(12x^2+9x)x−63×x23x+4x2 = x3−6x212x2+9x
Factor out xx from top and bottom.
(cancel(x)^1(x^2-6))/(cancel(x)^1(12x+9))