(\(\frac{2}{3}\))m (\(\frac{3}{4}\))n = \(\frac{256}{729}\)

\(\frac{2^m}{4^n}\) x \(\frac{3^n}{3^m}\) = \(\frac{2^{8}}{3^{6}}\)

\(2^{m} \div 2^{2n} = 2^{8}; 3^{n} \div 3^{m} = 3^{-6}\)

m - 2n = 8........(i)

-m + n = -6........(ii)

Solving the equations simultaneously

m = 4, n = -2