La Chaussette Perdue, the Parisian self-service laundry, serves an average of 3,500 customers per month. The typical customer’s laundry process — one wash cycle and three dryer cycles — involves €3.20 in electricity and water costs. The price for that laundry process is €6.50. The fixed costs for running La Chaussette are €6,600 per month.

La Chaussette’s owners have installed a coin-operated detergent dispenser. They traded in the spare parts of a broken washer for it, so they didn’t incur any cash expenses. The unit cost per box of detergent is €0.25.

If La Chaussette sells the detergent for €0.50, what is the minimum number of boxes of detergent La Chaussette will have to sell per month for its total operations to break even?