$23$

C&A Fast Food has four activities in serving a customer: greet customer, take order, process order, and deliver order. Each activity is staffed by one employee $($for a total of four employees$).$ The processing time for each activity is given as follows:

$\backslash$table$[[$Activity$,\backslash$table$[[$Processing time per$],[$customer$]],\backslash$table$[[$Wage rate$],[($$ per hour