3) A tank initially holds 1000kg of a solution containing 20% salt by weight. A stream enters at a constant flow rate of 5kg/min containing 5% salt by weight, and a stream leaves at a constant mass flow rate of 10kg/min. The contents of the tank are wellstirred. Please calculate the following: a) Determine the time for the salt concentration in the tank to decrease to 10% by weight. b) Using the answer for part-a, calculate the total mass of the solution in the tank and the mass of salt in the tank