How many bottles of water will she drink?
It’s not just the present we should focus on, we also need to think about the future.
If 'think about the future' made you picture saving the planet — good job. Recycling is cool but doesn't solve puzzles. Your brain does. You need to focus on Helen’s future... Specifically, how many bottles will she end up drinking in total? The full bottles she got from the first recycling, she’ll drink them, then she’ll recycle the empties. Get more. Drink again. It's the hydration circle of life. Stay hydrated too. Be more like Helen.
"8 bottles." From the initial 25 empty ones, she gets 6 full bottles and has 1 empty left. She drinks the 6, adding 6 more empties - now she has 7. He trades 4 of them for 1 more full bottle, drinks it, and ends up with 4 empties again. With those last 4, she gets one final bottle. (6+1+1=8).
