Does he pour 2/3 cups for everyone or total?
Everyone
If he pours 2/3 cups for everyone, that's 2/3*3 = 6/3 = 2
Then he does that for 30 days. That's 2cups*30 = 60 cups
1 quarter = 1/4
60 / 0,25 = 240
240 quarts
In total
If he pours 2/3 cups in total, that's 2/3 cups * 30 = 60/3 = 20 cups
1 quarter = 1/4
20 / 0,25 = 80
80 quarts