A tank contains  L of pure water.

After that brine pours a water into the tank at a rate of L/min.

Therefore the number of liters of water in the tank is .

The tank starts with no salt in it, later brine pours a g of salt per liter of water.

Hence the number of grams of salt in the tank is .

Therefore the concentration of salt is

.

(b)

Find the concentration of salt as .

As tends to then the concentration of salt in the tank approaches to g/L, which is the same as the concentration of salt in the brine.

.

(a) The concentration of salt is .

(b) .