
Patrick B. answered 02/19/19
Math and computer tutor/teacher
There are no constraints given, that's the problem.
It should say the factory has D_p days available for paining and D_a days available for assembly.
THe objective profit function is Profit(T,C) = 300*t + 200*c where t and c are the number of trucks and cars produced.
The time constraint for paining is T/40 + C/60 <= D_p
The time constraint for assembly is T/50 + C/50 <= D_a
(T+C)/50 <= D_a
T+C <= D_a*50
C <= D_a*50 - T
You can now solve this system by substitution, once you get these threshold constraints.
BTW, a good website for graphing is www.desmos.com