help

$\frac{12}{15}:\frac{4}{45}=\frac{12}{15}*\frac{45}{4}=\frac{3}{1}*\frac{3}{1}=3*3=9$

$\frac{12}{15}\div \frac{4}{45}\\ = \frac{\not4}{\not5}\times \frac{\not{45}^{\;9}}{\not4\;}$

= 9.

Same as Omi67's answer.