Given problem: Tank A contains 203 litres of brine holding 112 N of dissolved salt, and tank B contains 203 litres of fresh water. If brine runs out of tank A into tank B at the rate of 14 litres/min...

Given problem:

Tank A contains 203 litres of brine holding 112 N of dissolved salt, and tank B contains 203 litres of fresh water. If brine runs out of tank A into tank B at the rate of 14 litres/min while the mixture, kept thoroughly stirred, is pumped back to the tank A from tank B at the rate of 14 litres/min. When (in min) will the amount of salt in tank A be twice that in tank B? (Hint: The total amount of salt in both tanks at any time is 112 N.)