Price of an environmentally friendly water bottle is $10 and the variable cost is $5.50. At this price, 4000 bottles are sold in July 2017. If in August 2017, the price of the bottle is dropped by 5%, how many units of bottles should be sold to maintain the contribution margin as it was in July 2017. In addition, if in August 2017, the variable cost also increases by $800, what would be the new break even sales?

(Do write out your assumptions, if any)