P, Q and R together can do a piece of work in 56 days. P and Q together can do one-fourth as much work as R alone. In how many days can P and Q together complete the entire work?
An aeroplane when flying at a height of 5000 m from the ground passes vertically above another aeroplane at an instant, when the angles of elevation of the two aeroplanes from the same point on the ground are 60° and 45° respectively, the vertical distance between the aeroplanes at that instant is:
A, B and C can individually complete a task in 24 days,16 days and 32 days respectively. If A and C start the work and worked for 6 days and left, then the number of days required by B to complete the remaining task, is :