In trianglethere is pointABCDon line segmentAB, so that $\displaystyle |AD|:|DB|=2:1$, and there is pointEonBC, so that $\displaystyle |BE|:|EC|=1:4$. PointFis the point where line segmentsAEandDCintersect. Express the relationship (ratio) between $\displaystyle |AF|:|FE|$ ($\displaystyle \vec{AB}=\vec{a}$, $\displaystyle \vec{BC}=\vec{b}$).