Final answer:
The decision variables are the number of model A gates produced and the number of model B gates produced. The objective function is to maximize the profit. The constraints are the available steel and zinc.
Step-by-step explanation:
a) The decision variables in this problem are the number of model A gates produced and the number of model B gates produced. Let's denote the number of model A gates as 'x' and the number of model B gates as 'y'. So, the decision variables are x and y.
b) The objective function is the function that we want to maximize or minimize. In this case, we want to maximize the profit. The objective function can be expressed as: Profit = 90x + 70y, where x is the number of model A gates and y is the number of model B gates.
c) The constraints of the problem are the limitations or restrictions that we need to consider. In this case, the constraints are the available steel and zinc. The constraint for steel is: 150x + 100y ≤ 25000. The constraint for zinc is: 20x + 30y ≤ 6000.
d) Yes, there are sign and type restrictions in this formulation. The decision variables x and y must be non-negative, as the company cannot produce a negative number of gates. The constraints also have type restrictions, as they are inequalities that limit the amount of steel and zinc used.