Let P, Q, R and S denote the number of units of each model produced per

month.

Then the profit:

Pr=35*P+40*Q+20*R+50*S.

This is your objective to be maximised.

Constraints:

P>=0, Q>=0, R>=0, S>=0.

cutting constraint:

P+2*Q+2*R+3*S<=200

I will leave the assembly and painting constraints for you to fill in.

RonL