Answer:
tree is about 18.82 ft high
Explanation:
The triangles (that are formed by the tree and the poll with their shadows and the line from top to the end of the shadow) are in proportion because they cast the shadow at the same time.
x/9 = 23/11 , we write the proportions
x = 23*9 / 11, multiply both sides by 9
x ≈ 18.82 ft.