Question 1193347
He has 3*5 3/8 liters or 15 9/8 liters to fill or 16 1/8 liters
He has 20 5/6 liters.
couple of ways to do this.
From 16 1/8 liters to 20 liters is 3 7/8 liter
Then he needs 5/6 liter more
so add 3 7/8 and 5/6.
Just add 7/8 and 5/6 and later add 3.
common denominator is 24, so it is 21/24 and 20/24 which is 41/24 or 1 17/24
Add 3 for the answer and it is 4 17/24 liters, the answer
Check with decimals-5.375*3=16.125 liters
subtract from 20.833 liters to get 4.708 liters. 
17/24=0.7083 liters