The following is a table of activities associated with a project at Rafay Ishfaq's software firm in Chicago, their durations,

what activities each must precede and the crash cost to reduce duration per week:

Suppose that Rafay is only given $5$ weeks $($instead of $7)$ to complete the project. By how many weeks should each

activity be crashed in order to meet the deadline? Assume that you can crash an activity down to $0$ weeks duration.