Problems 1-3 : Find the missing length indicated. Problem 1 : Problem 2 : Problem 3 : Problem 4 : Solve for x. Problem 5 : Solve for x. Problem 6 : Solve for x. Problem 7 : Solve for x. 1. Answer : In the triangle shown above, line segment ED is parallel to the side BD. By Triangle Proportionality Theorem, AD/DB = AE/EC. Substitute. AD/18 = 20/8.