Two airplanes pass each other in flight while travelling in opposite directions. Each airplane continues on its flight for 45 minutes, after which time the airplanes are 840 km apart. The speed of the first airplane is 3/4 of the speed of the other airplane. Calculate the average speed of each plane.
The cooling system of Ennio's car contains 7.5 L of coolant, which is 100/3 % antifreeze. How much of this solution must be drained from the system and replaced with 100% antifreeze so that the solution in the cooling system will contain 50% antifreeze?
A car leaves Melbourne at 8 a.m travelling at a constant speed of 80 km/hr.it is followed at 10 a.m by another car travelling at constant speed of 110 km/hr on the same road. At what time will the second car overtake the first ?