There was twice as much water in container b as container a at first. then 1/6 of the water in container b is poured into container a. there 1.8 liters more water in container b than container a . what was the amount of water in container b at first?

Let be B = how much water is in container B;
A =  how much water is in container A;
B = 2A;
B - ( 1 / 6 )B = A + ( 1 / 6 )B + 1.8 ;
Then, 2A - ( 2A ) / 6 = A + ( 2A ) / 6 + 18 / 10 ;
2A - A / 3 = A + A / 3 + 9 / 5 ;
30A / 15 - 5A / 15 = 15A / 15 + 5A / 15 + 27 / 15 ;
30A - 5A = 15A + 5A + 27 ;
25A = 20A + 27 ;
5A = 27 ;
A = 27 / 5 ;
A = 5.4 liters;
B = 2 × 5.4 = 10.8 liters ;