Answer:
If the two triangles are equivalent, then all the measures of triangle 2 are k times the measures of triangle 1.
This means that:
BC = k*XY
here we know that:
BC = 8
XY = 20
then:
8 = k*20
8/20 = k
0.4 = k
Then we also will have the relation:
BD = 0.4*XZ
and we know that:
BD = 6
then:
6 = 0.4*XZ
6/0.4 = XZ
15 = XZ
Answering the question, the relationship between the corresponding angle bisectors is:
BD/XZ = 6/15 = 0.4