It's not a quadratic equation. The general form of a quadratic ecuation is:
[tex]ax^2+bx+c[/tex] - the second grade ecuation
We don't have here the unknown therm raised to the second power x² so we would solve the first grade ecuation.
[tex]3m+8=15 \\\\ 3m=15-8 \\\\ 3m=7 \\\\ \boxed{m=\frac{7}{3}} [/tex]
