A 600-gaJlon tank is filled with 300 gal of pure water. A spigot is opened and a sa1t solution containing 1 lb of sa1t per gallon of solution begins flowing into the tank at a rate of 3 gal/min. Simultaneously a drain is opened at the bottom of the tank a1lowing the solution to leave the tank at a rate of 1 gal/min. What will be the salt content in the tank at the precise moment that the volume of solution in the tank reaches the tank's capacity of 600 ga1?