Vector Algebra

Let $\overrightarrow a ,\overrightarrow b$ and $\overrightarrow c$ be three non-zero vectors such that no two of these are collinear. If the vector $\overrightarrow a + 2\overrightarrow b$ is collinear with $\overrightarrow c$ and $\overrightarrow b + 3\overrightarrow c$ is collinear with $\overrightarrow a$ ($\lambda$ being some non-zero scalar) then $\overrightarrow a + 2\overrightarrow b + 6\overrightarrow c$ equals to :