Round 4,868 to the nearest hundred

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;

The line y = x + passes through (−3, 7) and is parallel to y = 4x − 1.

Which of these triangle pairs can be mapped to each other using two reflections?