Phil's army surplus calculator business was going great guns especially the newest models with exclusive camouflage color schemes. these calculators blended into a variety of backgrounds making them virtually invisible to everyone except those equipped with polarized "cheep" sunglasses. phil sold the calculators and sunglasses combination package from his own dedicated web site: phil-the-bill. com. the packages sold for $44 earning phil a margin of 46% percent. shipping was extra. he also sold the calculator polarized glasses combination for the same price through an online department store, bigmuddy. com. bigmuddy earns a 15% commission on sales resulting from clickthroughs originating from bigmuddy. the latter accounts for 15% of total unit sales and somewhat less of dollar sales after commissions were paid. weekly sales of the combination package are 660 units.

if phil offers an electronic coupon for 10% off the price of sales through bigmuddy and bigmuddy's dollar margins remain unchanged, what unit increase will be required to increase weekly contribution dollars from bigmuddy sales by 25%? assume zero cannibalization.