\(\left(\dfrac{3}{4}\right).\left(\dfrac{-3}{4}\right)^{-4}=\left(\dfrac{3}{4}\right).\left(-1\right)^{-4}.\left(\dfrac{3}{4}\right)^{-4}=\left(\dfrac{3}{4}\right).1.\left(\dfrac{4}{3}\right)^4=\dfrac{3}{4}.\dfrac{4^4}{3^4}=\dfrac{4^3}{3^3}=\dfrac{64}{27}\)