Answer quickly for thumbs up read values properly

(Answer is 0.328kg)

A tank holds 100L of water into which 4kg of salt is dissolved. Water runs into the tank at the rate of 5 L per minute and salt solution overflows at the same rate. If the mixing in the tank is adequate to keep the concentration of the salt in the tank uniform, how much salt is in the tank at the end of 50 minutes? Assume that the density of the salt solution is essentially the same as that of water