I really need help in this one I’m stuck if someone could help me I would REALLY appreciate it ☹️ it’s geometry

In triangle abc segment de is parallel to the side ac . (the endpoints of segment de lie on the sides ab and bc respectively). find de, if ac=20cm, ab=17cm, and bd=11.9cm;

Using two or more complete sentences, describe how you can find a vector parallel to b=-2,3

The estimated number of people to attend the last bengals game of the season was 2000. the actual number of fans attending was 1200. by what percent did the estimate differ from the actual?