Could you help me to explain the method to have the right result. Thanks in advance.

Kimpel Products makes pizza ovens for commercial use. James Kimpel, CEO, is contemplating producing smaller ovens for use in high school and college kitchens. The activities necessary to build an experimental model and related data are listed in the following table: Total Cost Normal Time Crash Time Normal with Immediate Activity (weeks) (weeks) Cost Crashing Predecessor(s) $1,000 $1,700 $2,000 $2,800 $350 $350 NOW ON ANDJANO $1,500 $1,800 A $850 $1,000 B $4,250 $5,450 $1,800 $2,500 D, Ea) Based on the given information regarding the activities for the project, the project completion date = 14 weeks. b) To reduce the duration of the project to 10 weeks at the least cost, the following is the order of what needs to be followed while crashing the activities: The first activity to crash is D by 2 weeks at a per week crashing cost of 75 dollars. Next, one should crash activity D and activity E by 2 weeks for an additional total per week crashing cost of 125 dollars. c) New requirements are to reduce the project to 7 weeks. Continuing to crash the activities from 10 weeks based on the above crashing already completed, the following is the order for crashing: Next activity to crash in order is G by 2 weeks at a per week crashing cost of 350 dollars. Next, one should crash activity A and activity E by 1 week at a total per week crashing cost of 750 dollars. Total cost of crashing the project to 7 weeks = 1,850 dollars