There are two tanks. The first tank has a salt solution with 50 g salt per 100 L solution. The salt solution from the 1st tank flows to the 2nd tank with a flow rate of 1 L/min. At the same time, salt solution from the 2nd tank flows to the 1st tank with a flow rate of 1 L/min. If both tanks are well-mixed, find the salt amount in the 2nd tank after 10 minutes.