Bucket of water. You have brought two unmarked buckets to a stream. The buckets hold 7 gallons and 3 gallons of water, respectively. How can you obtain exactly 5 gallons of water to take home?

4 (3) - (7) = 5

2 (7) - 3 (3) = 5

Step-by-step explanation:

Fill the empty 3-gallon bucket 4 times and transfer the contents to the 7-gallon bucket. When the 7-gallon bucket is full, empty it. After the 4th time the 3-gallon bucket is emptied, the 7-gallon bucket will contain 5 gallons.

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Alternatively, fill the empty 7-gallon bucket twice and transfer the contents to the 3-gallon bucket. Each time the 3-gallon bucket is full, empty it. After the 3rd time the 3-gallon bucket is emptied, the 7-gallon bucket will contain 5 gallons.