We can write the length of DB like this:
[tex]4.5=\frac{9}{2}[/tex]Now, to find the scale factor of the dilation, we have to solve for k the following equation:
[tex]\frac{9}{2}k=18[/tex]then, we have the following:
[tex]\begin{gathered} \frac{9}{2}k=18 \\ \Rightarrow9k=18\cdot2=36 \\ \Rightarrow k=\frac{36}{9}=4 \\ k=4 \end{gathered}[/tex]therefore, the scale factor is k=4
