**THIS CODE WAS WRITTEN FOR THE CONSTRAINT-BASED MODELING WORKSHOP J.REED (1/2008)    
*Consider two variables A and B, which are the amount of toy cars and trucks you can produce.

*Do to resource limitations you can make no more than 60 cars a day and no more than 50 trucks a day.
*   0 <= cars <= 60
*   0 <= trucks <= 50

*You are also limited by shipping such that the number of cars plus twice the number of trucks must be less than 150.
*   cars + 2*trucks <= 150

*You can sell the toys at $20/car and $30/truck your earnings (Z) are given by:
*   profit = 20*cars + 30*trucks


variables
cars
trucks
profit;

equations
constraint1
constraint2
constraint3
earnings;

constraint1.. cars=l=60;
constraint2.. trucks=l=50;
constraint3.. cars+2*trucks=l=150;
earnings.. profit=e=20*cars+30*trucks;

cars.lo=0;
trucks.lo=0;

model production /all/;
solve production using lp maximizing profit;