Schedule of Activity Costs Quality Control Activities Process audits Training of machine operators Processing returned products Scrap processing (disposal) Rework Activity Cost $48,900 27,000 17,700 24,800 6,200 27,600 41,600 Preventative maintenance Product design Warranty work Finished goods inspection From the above schedule of activity costs, determine the value-added costs. Oa. $175,700 Ob. $167,500 Oc. $145,100 Od. $224,400 8,200 22,400