A tank contains 1000L of brine with a concentration of .5kb of salt per liter. In order to dilute the solution, brine with a concentration of 0.1kg of salt per liter runs into the tank at a rate of 20L/min and the resulting solution, which is stirred continuously, runs out at the same rate. How many kilograms of salt will remain after t minutes?

From skimming this, did I make any mistakes?