(25 points) A very large tank initially contains 100L of pure water. Starting at time ( = 0 a solution with a salt concentration of 0.3kg/L is added at a rate of 7Ly min. The solution is kept thoroughly mixed and is drained from the tank at a rate of SL/ min. Answer the following questions. 1. Let y(t ) be the amount of salt (in kilograms) in the tank after f minutes. What differential equation does y satisty? Use the vanabie y for y(t ). dy Answer (In kilograms per minute): 2. How much salt is in the tank after 40 minutes? Answer (In kilograms)