If m RST = (12x - 1) , m RSU = (9x - 15) , and m UST = 53 , what is m RST

We have the following:
[tex]\begin{gathered} 12x-1-53=9x-15 \\ 12x-9x=1+53-15 \\ 3x=39 \\ x=\frac{39}{3}=13 \end{gathered}[/tex]therefore:
RST:
[tex]12\cdot13-1=155[/tex]therefore RST is 155°