Please help im tired :( quadratic formulas

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .

Answers4.) -1/205.) -1/406.) -55/127.) -3/4

9.8? i'm not really sure