please explain how you get answer for b

Development of Version 2.0 of a particular accounting software product is being considered by Joso Noguera's technology firm in Baton Rouge. The activities necessary for the completion of this project are listed in the following table: Activity B D E F G Normal Time Crash Time Normal (weeks) (Weeks) Cost 4 3 $2,100 2 1 $2.300 3 3 3500 8 4 $2,500 6 3 $900 3 2 $3,000 4 2 $1.500 Total Cost with Immediate Crashing Predecessor(s) $2.700 $3,000 $500 $2,800 $1,350 $4,400 $1,900 DE a) Based on the given information regarding the activities for the project, the project length = 16 weeks b) The total cost required for completing this project on normal time = $