For each tree: The bottom of the tree, the top of the tree, and the tip of the shadow form a triangle. These two triangles associated with the two trees are similar because all three corresponding angles of the two triangles are equal.
Because the triangles are similar, the ratio of the shadow length (horizontal leg) to the tree height (vertical leg) is the same for both trees. Converting the inches into decimal fractions of a foot, those two equal ratios are 11.25/10.5= 17.5/x, where x is the height of the second tree. Solving for x gives 16.3333333 feet, with is 16 plus 1/3 foot. Since 1/3 foot is 4 inches, the answer is A=16, B=4.
