Pour into the first barrel: 14× 1/7=2 liters.
The first barrel: before pouring, there is 12-2= 10 liter, which is 2/3 of the original.
So the first barrel originally had: 10÷2/3= 15 liters.
15× 1/3=5 liters.
After the second barrel is poured into the third barrel, there is 12 liter, which is 3/4 of that before being poured into the third barrel.
So there is 12÷3/4= 16 liters before pouring into the third bucket.
16-5= 1 1
The first barrel initially contained 15 liter, the second barrel initially contained 1 1 liter, and the third barrel initially contained 10 liter.
If you are satisfied, please adopt it and give an encouragement. Thank you.