You're going to mix a gallon bucket of window cleaner. The instructions direct you to mix 1 part cleaner to 3 parts water. How many cases do you need to order to have enough for 7 days ?
so if you use 1 part cleaner and 3 parts water for 1 day and each case holds 1 gallon of cleaner then you need 1 case for each day so for 7 days you would need 7 cases