What is the length of segment DF

Ascatterplot is produced to compare the size of a school building to the number of students at that school who play an instrument. there are 12 data points, each representing a different school. the points are widely dispersed on the scatterplot without a pattern of grouping. which statement could be true

1. are the triangles similar and if so why? what is the value of x? show your work.

Which rational number could be graphed between -4 and -5