At present, two buckets respectively contain 10 L of salt water with a concentration of 15 g/L. Now, clean water is injected into the first bucket at the rate of 2L/min, and the second bucket is injected at the rate of 2L/min after stirring evenly, and then discharged from the second bucket at the rate of 2L/min. After 5min, how many grams of salt is contained in the second bucket？