You have coordinates of tree T(16,21) and of rock R(3,2). Let S be a point that denotes treasure. Since treasure is buried so that it partitions the distance between a rock and a tree in a 5:9 ratio, you can state that

Find the coordinates of these vectors:

Then
and
Solve these two equations:
1.

2.

Answer: the treasure are placed at point (7.6,8.8), so the correct choice is B.