80) 5 men or 9 women can do a piece of work 19 days. In how many days will 3 men and 6 women working together will finish the work?

81) Two pipes can fill a tank in 20 minutes will 30 minutes respectively. If both the pipes are opened simultaneously, then the tank will be filled in

82) A train 132 metre long passes a telegraph post in 6 seconds. The speed of the train is

83) The radius of the wheel of a vehicle is 70 cm. The wheel makes 10 revolutions in 5 seconds. The speed of the vehicle is

84) The area of the base of a rectangular tank is 6500 cm2 and the volume of water contained in it is 2.6 cubic metres. The depth of the water tank is