Answer:
Star Zinc should rework the defective units as it will produce a net cash flow of $15,000
Explanation:
The cost of producing the defective units is Irrelevant to the decision as to rework or to sell the defective units.
Option 1 Â Â Â Â Â Â
Rework: Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â $
Sales revenue from sale = (100×200) =  20,000
Relevant cost            (25× 200) =  5000
Net cash flow                       15,000
Option 2: Outright sale
Revenue from outright sales = 35× 200 = 7,000
Star Zinc should rework the defective units as it will produce a net cash flow of $15,000.