Triangle A B C is cut by line segment D E. Line segment D E goes from side A B to B C. Lines A C and D E are parallel. The length of A D is 3, the length of D B is 5, the length of B E is 4, and the length of E C is question mark. StartFraction B D Over D A EndFraction = StartFraction B E Over E C EndFraction. StartFraction 5 Over 3 EndFraction = StartFraction 4 Over E C EndFraction