Hawkins Manufacturing Company produces connecting rods for 4- and 6-cylinder auto-
mobile engines using the same production line. The cost required to set up the production
line to produce the 4-cylinder connecting rods is $2,000, and the cost required to set up the
production line for the 6-cylinder connecting rods is $3,500. Manufacturing costs are $15
for each 4-cylinder connecting rod and $18 for each 6-cylinder connecting rod. There is no
production on weekends, so on Friday the line is diassembled and cleaned. On Monday,
the line must be set up to run whichever product will be produced that week. Once the line
has been set up, the weekly production capacities are 6000 6-cylinder connecting rods and
8000 4-cylinder connecting rods. Let
x4 5 the number of 4-cylinder connecting rods produced next week
x6 5 the number of 6-cylinder connecting rods produced next week
s4 5 1 if the production line is set up to produce the 4-cylinder connecting rods; 0 if otherwise
s6 5 1 if the production line is set up to produce the 6-cylinder connecting rods; 0 if
otherwise

a. Using the decision variables x4 and s4, write a constraint that sets next week