For this we want to switch the sides to start out.
-3t + 6 < -3
Now we want to subtract 6 from both sides...
-3t + 6 - 6 < -3 - 6
Simplify it.
-3t < -9
Now we want to reverse the inequality and multiply both sides by -1
(-3t) (-1) > (-9)(-1)
Simplify yet again.
3t > 9
Divide both sides by 3 now.
3t/3 > 9/3
Now we can say that t > 3.
Hope this helps!