Keep in mind that, when the logarithm base is not explicitly written, base 10 is assumed, therefore,
16 ft
Explanation
Step 1
because the ligth comes in the same angle, we have 2 similar triangles .
so,as the triangles are similar,the ratio of the shorter leg to the bigger leg must be equal.
Step 2
solve for h
therefore, the heigth of the tree is 16 ft