Answer:
x = 6
Step-by-step explanation:
[tex] \because ST \: bisects\: \angle RSV\\
\therefore m\angle RST = m\angle VST\\
(by\: \angle \: bisector \: property) \\
\therefore 5x - 3 = 2x + 15\\
\therefore 5x - 2x = 15 +3\\
\purple{\bold {\therefore 3x = 18}} \\
\therefore x =\frac{18}{3}\\
\huge \orange {\boxed {\therefore x = 6}} [/tex]