You are going to mix a gallon bucket of window cleaner. the instructions direct you to mix 1 part cleaner to 3 parts water. how much cleaning solution will you need to use?

You would need 1 quart of cleaning solution.

This is because you need a gallon of window cleaner, right?  This is made up of 1 part window cleaner and 3 parts of water.  3+1=4 parts total.  1 gallon / 4 parts = 1 quart.  So each of these "parts" is equal to one quart of liquid.  Therefore, you will need to use one quart of cleaning solution.