Answer
$t=-1$
Work Step by Step
The distributive property allows us to distribute anything multiplied by something inside of the parenthesis to whatever is inside of the parenthesis. Thus, we distribute the -2 to everything inside of the first set of parenthesis and the -3 to everything inside of the second set of parenthesis, giving us the equation -3t+12-2t-8=9. We now simplify:
$-5t+4=9 \\\\ -5t=5 \\\\ t=-1$