Let $V$ be a vector space, $v, u \in V$, and let $T_1: V \rightarrow V$ and $T_2: V \rightarrow V$ be linear transformations such that $$T_1(v) = 3 v + 3 u, \ \ \ T_1(u) = -4 v + 7 u,$$ $$T_2(v) = 2 v + 4 u, \ \ \ T_2(u) = 6 v + 6 u.$$ Find the images of $v$ and $u$ under the composite of $T_1$ and $T_2$.

$(T_2 T_1)(v) =$ ,
$(T_2 T_1)(u) =$ .