We have indeterminateness of type
0/0,
i.e. limit for the numerator is
$$\lim_{x \to 0^+} \sin{\left(\tan{\left(2 x \right)} \right)} = 0$$
and limit for the denominator is
$$\lim_{x \to 0^+} \operatorname{asin}{\left(3 x \right)} = 0$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{x \to 0^+}\left(\frac{\sin{\left(\tan{\left(2 x \right)} \right)}}{\operatorname{asin}{\left(3 x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \sin{\left(\tan{\left(2 x \right)} \right)}}{\frac{d}{d x} \operatorname{asin}{\left(3 x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\sqrt{1 - 9 x^{2}} \left(2 \tan^{2}{\left(2 x \right)} + 2\right) \cos{\left(\tan{\left(2 x \right)} \right)}}{3}\right)$$
=
$$\lim_{x \to 0^+} \frac{2}{3}$$
=
$$\lim_{x \to 0^+} \frac{2}{3}$$
=
$$\frac{2}{3}$$
It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 1 time(s)