Given the information on the picture, notice that we have the following relationship between sides CA and CA' :
[tex]CA^{\prime}=k\cdot CA[/tex]where k is the scale factor.
If we use the measures given and solve for k, we have:
[tex]\begin{gathered} 10=k\cdot5 \\ \Rightarrow k=\frac{10}{5}=2 \\ k=2 \end{gathered}[/tex]therefore, the scale factor is k = 2
