Let \(\rm \vec{{a}}=\hat{{i}}+2 \hat{{j}}+3 \hat{{k}}\), \(\rm \vec{{b}}=2 \hat{{i}}+3 \hat{{j}}-5 \hat{{k}}\) and \(\rm \vec{{c}}=3 \hat{{i}}-\hat{{j}}+λ \hat{{k}}\) be three vectors. Let \(\rm \vec{{r}}\) be a unit vector along  \(\rm \vec{b}+\vec{c}\). If  \(\rm \vec{r}. \vec{a}=3\), then 3 λ is equal to: