$-3t\div\left( -3 \right) < -6\div\left( -3 \right)$
Any expression divided by itself equals $1$$t < -6\div\left( -3 \right)$
Dividing two negatives equals a positive: $\left( - \right)\div\left( - \right)=\left( + \right)$$t < 6\div3$
Calculate the quotient$\begin{align*}&t < 2 \\&\begin{array} { l }t \in \langle-\infty, 2\rangle\end{array}\end{align*}$