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

85) Two angles are complementary, if the sum of their measures is