Any similar triangle the ratio of corresponding length is equal.
that mean:
Then:
[tex]\frac{AB}{XY}=\frac{BC}{YZ}=\frac{AC}{XZ}[/tex]Similarly :
[tex]\frac{ED}{CB}=\frac{EA}{CA}=\frac{DA}{BA}[/tex]let CA is x then:
[tex]\begin{gathered} \frac{ED}{CB}=\frac{EA}{CA} \\ \frac{10}{5}=\frac{12}{x} \\ x=\frac{12\times5}{10} \\ x=6 \end{gathered}[/tex]so value of CA is 6 units.