Let the large mixing tank with initially 200 gallons of water with dissolved 30 pounds of salt. Pure water is pumped into tank with rate of 2 gal/min, and when solution is well stirred, it is pumped out. Write the differential equation for amount of salt A(t) in tank at t > 0 if
i) solution is pumped out at same rate;
ii) solution is pumped out at the faster rate of 3 gal/min.
Find A(0).