Resposta :
[tex]x_M=\frac{x_A+x_B}{2}= \\
-9=\frac{13+x_B}{2} \rightarrow 13+x_B=-18 \rightarrow x_B=-18-13=-33 \\
\\
y_M=\frac{y_A+y_B}{2} \\ 30=\frac{19+y_B}{2} \rightarrow19+y_B=60 \rightarrow y_B=60-19=41 \\
\\
\boxed{B(-33,41)}[/tex]