This is the basic and conceptual question from trigonometry (height and distance) in which we are to find the height of the tower PQ, if the angle of elevation of the top Q of a vertical tower PQ from a point X on the ground is 60∘. From a point Y, 40 m vertically above X, the angle of elevation of the top Q of tower is 45∘.
Book RS Aggarwal, Class 10, chapter 14, question no 24.
Hope it helps you.