Explanation

Create a cross-multiplying diagram and fill it in with values from the question:

	Tree 1:	Tree 2:
Real height:	12 ft.	? ft.
Shadow height:	8 ft.	10 ft.

(8)(?) = (12)(10) → (8)(?) = 120 → ? = 15

Hence D is the correct option.
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The two poles and their shadows are forming the two legs of similar right triangles. As such, we can make a ratio:

height1/shadow1 = height2/shadow2

so

12/8 = h/10

which tells us that the height is 15. The answer is D.
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Isnt it 8/12 = 10/x ?
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