A house flipper found a diamond in the rough and, after buying it at a sheriff's auction, has identified six systems that need significant work. The estimated completion times (in weeks) and costs are identified in the table alongside a set of expedited completion times and the crash costs. Activity Normal time Crash time Normal Cost Crash Cost Predecessor A 10 7 5,000 7,200 B 15 10 10,000 15,000 A C 20 15 18,000 24,000 B D 20 17 20,000 26,000 E 15 12 12,000 14,700 D F 12 7 7,200 12,700 [] E What is the lowest cost to complete this project as quickly as possible?