Answer
Here are the contents of the containers after each stage:
A B
0 11 fill B
7 4 fill A from B
0 4 empty A
4 0 fill A from B
4 11 fill B
7 8 fill A from B
0 8 empty A
7 1 fill A from B
0 1 empty A
1 0 fill A from B
1 11 fill B
7 5 fill A from B
0 5 empty A
5 0 fill A from B
5 11 fill B
7 9 fill A from B
0 9 empty A
This leaves 9 gallons in container B.
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Puzzle 190
Below is a very special grid, around each shaded number are 8 white squares.
However, each white square should have a number from 1 to 7.
Once filled in, these 8 numbers will sum to the shaded number.
In addition, once completed correctly, no row nor column will contain a duplicate number within a white square.
For example, the top row may be 5 6 4 2 3 1 7, etc.
This is a very difficult puzzle, and many people resort to using a computer to help them, which is a challenge in itself.
These are the positions of the letters of the alphabet, and they are spelling Donkey.
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Puzzle 192
My BrainBashers electronic world atlas has developed a fault, I did a listing of miles from Scotland to particular countries, and here is the result:
England 12,000 miles
Peru 6,000 miles
Egypt 9,000 miles
Iceland 11,000 miles