Answer:
[tex]=\left(-\frac{9}{2},\:-\frac{11}{2}\right)[/tex]
Step-by-step explanation:
[tex]\mathrm{Midpoint\:of\:}\left(x_1,\:y_1\right),\:\left(x_2,\:y_2\right):\\\quad \left(\frac{x_2+x_1}{2},\:\:\frac{y_2+y_1}{2}\right)\\\\\left(x_1,\:y_1\right)=\left(-12,\:-3\right),\:\left(x_2,\:y_2\right)=\left(3,\:-8\right)\\\\=\left(\frac{3-12}{2},\:\frac{-8-3}{2}\right)\\\\=\left(-\frac{9}{2},\:-\frac{11}{2}\right)[/tex]