Let us try to represent the question as an image.
From the diagram, we can get a triangle by considering the tree and shadow, such that
The angle x° is the angle of elevation of the sun,
To find the angle x°, we will use one of the Trigonometric Ratios, in this case, the Tan ratio.
Hence,
where
opp = 12 yards
adj = 15 yards
Substituting,
The angle of elevation of the sun, to the nearest degree, is 39°