Chang industries has 1,400 defective units of product that have already cost $13.40 each to produce. a salvage company will purchase the defective units as they are for $4.40 each. chang's production manager reports that the defects can be corrected for $6.60 per unit, enabling them to be sold at their regular market price of $19.80. the incremental income or loss on reworking the units is: