Let \( f \) be a differentiable function such that \( x^{2} f(x)-x=4 \int_{0}^{x} t f(t) d t, f(1)=\frac{2}{3} \). Then …

Let \( f \) be a differentiable function such that \( x^{2} f(x)-x=4 \int_{0}^{x} t f(t) d t, f(1)=\frac{2}{3} \). Then \( 18 f(3) \) is equal to

[JEE Main 2023, 10 Apr (Shift 1)]