Explanation:
let chairs be C and sofas be S
The objective function is
Maximize
90C+75S=P
The constraints are
carpentry
3C+2S=66------1
finishing
9C+4S=180-----2
upholstery
2C+10S=200-----3
C>0, S>0
The linear programming is
3C+2S=66
9C+4S=180
2C+10S=200