$\begin{array}{l}
\left( {12x - {4^3}} \right){.8^3} = {4.8^4}\\
\left( {12x - {4^3}} \right).{\left( {{2^3}} \right)^3} = {2^2}.{\left( {{2^3}} \right)^4}\\
\left( {12x - {4^3}} \right){.2^9} = {2^2}{.2^{12}}\\
\left( {12x - {4^3}} \right){.2^9} = {2^{14}}\\
12x - {4^3} = {2^{14}}:{2^9}\\
12x - {4^3} = {2^5}\\
12x = {2^5} + {4^3}\\
12x = 32 + 64\\
12x = 96\\
x = 96:12\\
x = 8
\end{array}$
