Here is one way,Originally Posted byamandamom

Good for 7 days:

At 2 bottles per day, 7*2 = 14 bottles sales

Minimum of 6 bottles always on shelf

Add those up and you need minimum of 20 bottles for the next 7 days,

You have now 12 bottles.

20 minus 12 is 8 bottles

Therefore you need to order minimum of 8 bottles. -------answer.

!4 bottles is okay, but that is not the minimum.