Answer: $0.64
Explanation:
We don't need the details about the daily recommended consumption of water or the price of a water unit at the supermarket. The essential details are:
- The cost of a year's supply of bottled water is $911.85.
- The cost of drinking tap water for a year is $911.21 less.
As such, the cost of drinking tap water for a year is $911.85 - $911.21 = $0.64.