Triangle BCA is similar to Triangle STR . What is the value of x?

Sin the triangles are similar the ratio 4 to 6 should hold for any side, this means that:
[tex]\frac{4}{6}=\frac{x}{9}[/tex]Solving for x we have:
[tex]\begin{gathered} \frac{4}{6}=\frac{x}{9} \\ x=9(\frac{4}{6}) \\ x=\frac{36}{6} \\ x=6 \end{gathered}[/tex]Therefore. x=6.