Reasoning
From the initial 77 bottles, 75 bottles can be recycled for 15 new full bottles.
Once those are drunk, Alex will have 17 empty bottles (15 plus the 2 extra empty bottles).
From the 17 empty bottles, 15 bottles can be recycled for 3 new full bottles.
Once those are drunk, Alex will have 5 empty bottles (3 plus the 2 extra empty bottles), which can be recycled for one final full bottle.
Giving a total of 15 + 3 + 1 = 19.
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Puzzle 7
Start in square 'S' and end in square 'E' moving either horizontally or vertically in each move. Start by moving 2 squares in each of your moves, but when you land on a '*' square, change the number of squares you move from 2 to 3, or vice versa. You can not step on or pass through the black squares, and you have only 8 moves in which to complete this task.
