[tex] 9xy\cdot\left(\dfrac{2}{3}x\right)^3=9xy\cdot\dfrac{2^3}{3^3}x^3=9\cdot\dfrac{8}{27}\cdot xyx^3=\dfrac{8}{3}x^4y\\\\Used:\\\left(\dfrac{a}{b}\right)^n=\dfrac{a^n}{b^n}\\\\(a\cdot b)^n=a^n\cdot b^n\\\\a^n\cdot a^m=a^{n+m} [/tex]
[tex]\text{Answer:}\ \boxed{\left(\dfrac{8}{3}\right)}[/tex]