In triangle ABC there is point D on line segment AB, so that $|AD|:|DB|=2:1$, and there is point E on BC, so that $|BE|:|EC|=1:4$. Point F is the point where line segments AE and DC intersect. Express the relationship (ratio) between $|AF|:|FE|$ ( $\vec{AB}=\vec{a}$, $\vec{BC}=\vec{b}$).