Atank contains 1000 l of pure water. brine that contains 0.05 kg of salt per liter of water enters the tank at a rate of 5 l/min. brine that contains 0.04 kg of salt per liter of water enters the tank at a rate of 10 l/min. the solution is kept thoroughly mixed and drains from the tank at a rate of 15 l/min.

(a) how much salt is in the tank after t minutes? y = kg
(b) how much salt is in the tank after 40 minutes? (round the answer to one decimal place.) y(40) = kg