We use the proportion for this case the pole and the tree with their shadows has the same shape forming a right triangle.
We use the ratio of the two triangles and equate them as
h1/s1 = h2/s2
where
h1 and s1 are the height and the length of a shadow of the pole,
and the other h2 and s2 are for the tree
Identify all the given values.
5 ft / 2 ft = (h2) / 10 ft
h2 = 25 ft
Therefore the height of the tree "h2" is 25 ft.