Atank contains 200 gallons of water in which 300 grams of salt is dissolved. a brine solution containing 0.4 kilograms of salt per gallon of water is pumped into the tank at the rate of 5 gallons per minute, and the well-stirred mixture is pumped out at the same rate. let latex: a\left(t\right)a(t)[math processing error] represent the amount of salt (measured in kilograms) in the tank at time latex: t[math processing error].