Given that the triangle ABC and DEF are similar, therefore its corresponding sides must be proportional,
[tex]\begin{gathered} \frac{AB}{DE}=\frac{BC}{EF}=\frac{AC}{DF} \\ \frac{4}{6}=\frac{10}{y}=\frac{x}{12} \end{gathered}[/tex]
Comparing the first and third terms,
[tex]\begin{gathered} \frac{4}{6}=\frac{x}{12} \\ x=\frac{4}{6}\times12 \\ x=4\times2 \\ x=8 \end{gathered}[/tex]
Comparing the first and second terms,
[tex]\begin{gathered} \frac{4}{6}=\frac{10}{y} \\ y=\frac{6}{4}\times10 \\ y=3\times5 \\ y=15 \end{gathered}[/tex]
Thus, the values of 'x' and 'y' are 8 and 15, respectively.
