The angles of elevation of the top of a building from the top and bottom of a tree are x and y respectively. If the height of the tree is h meter then, in meter, the height of the building is:
A train leaves Amritsar at 6 am & reaches Delhi at 12 noon. Another train leaves Delhi at 8 am & reaches Amritsar at 5 pm. At what time do the two trains cross each other?