(6) A tank initially contains 30 lbs of salt dissolved in 1,000 gallons of water at time t = 0, Brine that contains 0.2 lbs of salt per gallon is pumped into the tank at 5 gallons per minute and the well-mixed solution is drained at the same rate (a) Determine a function y(t) for the amount of salt in the tank (in lbs) at time t20 Hint: y'(t) = rate (lbs/min) of salt coming rate (lbs/min) of salt going out. - y(t) =