From the top of a tower of height 180 m the angles of depression of two objects on either sides of the tower are 30° and 45°. Then the distance between the objects are
A runs \(1 {2 \over 3}\) times as fast as B. If A gives B a start of 80 m, how far must the winning post be so that A and B might reach it at the same time?
Pipe A can fill a tank in 12 minutes and pipe B can empty it in 6 minutes. If the tank is 50% full, and both pipes are opened together, then the tank will be completely empty after: