Apail contained 3.68l of water more than a bottle. after bill poured away 1.2l of water from the pail, the pail contained 3 times as much water as the bottle. (a) how much more water did the pail contain than the bottle in the end? (b) how much water did the bottle contain?

For the sake of simplicity, let us say that the bottle contains x liters of water.

The pail originally contained x+3.68 L of water
After pouring out 1.2L, the pail contains x+(3.68-1.2)L or x+2.48 L

(a) How much more water did the pail contain than the bottle in the end?
Since the bottle contains x L of water, the pail (containing x+2.48 L of water) contains (x+2.48) - x more liters of water than the bottle or "the pail contained 2.48 L of water more than the bottle"

(b) How much water did the bottle contain?
We are told that after pouring the 1.2L of water out, the pail contained 3 times as much water as the pail. Therefore, 3x = x+2.48. Subtracting x from both sides gives us 2x = 2.48. Dividing both sides by 2 gives us x = 1.24L