cost $$2700,$ upgrading the kitchen would cost $$2500,$ replacing the back window with a door would cost $$600,$ and installing a garage door opener would cost $$350.$

The landlord uses the following scheme for decision variables:

$\backslash$table$[[\backslash$table$[[x_1=$ contractor works on wood$],[$floors$]],\backslash$table$[[x_2=$ landlord works on wood$],[$floors$]]],[\backslash$table$[[x_3=$ contractor works on kitchen$],[$tile$]],\backslash$table$[[x_4=$ contractor works on kitche$],[$tile$]]],[\backslash$table$[[x_5=$ contractor works on back$],[$door$]],\backslash$table$[[x_6=$ contractor works on back$],[$door$]]],[\backslash$table$[[x_7=$ contractor works on garage$],[$door$]],\backslash$table$[[x_8=$ contractor works on garage$],[$door$]]]]$

What should the objective function be$?$

MinZ$=2700x_1-400x_2+2500x_3-1000x_4+600x_5-250x_6+350x_7-400x_8$

MaxZ$=100x_1-100x_2+80x_3-80x_4+15x_5+15x_6+20x_7-20x_8$

Maxz$=100x_1+100x_2+80x_3+80x_4+15x_5+15x_6+20x_7+20x_8$

MinZ$=2700x_1+400x_2+2500x_3+1000x_4+600x_5+250x_6+350x_7+400x_8$