solve the equation, help please

The answer is:   " x = - [tex] \frac{8}{7} [/tex] " ;  which is:  "Answer choice:  [C]" . 

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Explanation:
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16⁽ˣ⁻⁴⁾ = 64⁽³*ˣ⁾ ;

=(4²)⁽ˣ⁻⁴⁾ = (4³)⁽³*ˣ⁾


→  4^ [2(x-4)]  = 4^ [ 3(3x) ] ; 

→  4^ (2x - 8)  = 4^ (9x) ; 

→  2x - 8 = 9x ; 

Subtract "2x" from each side of the equation:

→  2x - 8 - 2x = 9x - 2x ; 

→  -8 = 7x ; 

→  7x = -8 ;

Divide EACH SIDE of the equation by "7" ; 
  to isolate "x" on one side of the equation; & to solve for "x" ; 

→  7x / 7 = -8 / 7 ; 
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→  x = - 8/7 ;  which is:  Answer choice:  [C]:  " - [tex] \frac{8}{7} [/tex] " .
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