Let \( f \) be a differentiable function such that \(\displaystyle x^{2}f(x)-x = 4\!\int_{0}^{x} t f(t)\,dt \), \( f(1)=\dfrac{2}{3} \). Then \( 18f(3) \) is equal to:
\( 160 \)
\( 180 \)
\( 210 \)
\( 150 \)