Proving Triangles

$\frac{3y-8}{12}=\frac{y}{5} \\~\\ \frac{5(3y-8)}{12}=y \\~\\ 5(3y-8) = 12y \\ 15y-40=12y \\ 15y=12y+40 \\ 3y=40 \\~\\ y = \frac{40}{3} = 13\frac{1}{3} \approx 13.333$