Answer quickly for thumbs up

(answer is 9048kg, t=6.93h)

A tank of capacity 50m3 is completely filled with a brine solution containing 20 mass\% solution of sodium chloride. Water is added at the rate of 5m3 per hour and brine is withdrawn at the same volumetric rate. Compute the mass of sodium chloride remaining in the tank after one hour. Also determine the time required for reducing the sodium chloride content of the solution in the tank to 10 mass\%. Assume thorough mixing in the tank and neglect density changes due to concentration