\(\left(\left(\frac{2}{3}\right)^x\right)^3=\frac{27}{8}\Rightarrow\left(\left(\frac{2}{3}\right)^x\right)^3=\left(\frac{3}{2}\right)^3\Rightarrow\left(\frac{2}{3}\right)^x=\frac{3}{2}\Rightarrow\left(\frac{2}{3}\right)^x=\left(\frac{2}{3}\right)^{-1}\Rightarrow x=-1\)