A tank contains 420 litres of a solution, with 20 kilograms ofsalt in the solution. A solution with a concentration of 57kilograms per litre enters the tank at a rate of 7 litres perminute. The well-stirred solution flows out of the tank at the samerate. Determine the mathematical model that gives the functiony(t), the number of kilograms of salt in the tank after tminutes
