question

You are given a 3-quart bucket, a 5-quart bucket, and an unlimited supply of water.
How can you measure out exactly 4 quarts?

Drawing a simple graphic may help.

Start by filling the 5-quart bucket completely. Use the 5-quart bucket to fill the 3-quart bucket -
leaving 2 quarts in the 5-quart bucket. Empty the 3-quart bucket and fill it with the 2 quarts from
the 5-quart bucket. Fill the 5-quart bucket. Fill the 3-quart bucket (which already has 2 quarts)
using the 5-quart bucket. This leaves exactly 4 quarts in the 5-quart bucket.