Final answer:
The total cost of each method of production is $90. The firm should use the new method because it is more cost-effective with a decreased cost of a machine.
Step-by-step explanation:
To determine the total cost of each method of production, we need to calculate the cost of labor and the cost of a machine for each method. Given that the cost of labor remains at $40 and the cost of a machine decreases to $50, we can calculate the total cost for each method.
For the first method (Old Method): Total cost = Cost of labor + Cost of machine = $40 + $50 = $90
For the second method (New Method): Total cost = Cost of labor + Cost of machine = $40 + $50 = $90
Both methods have the same total cost of $90. However, the firm should use the new method because it is more cost-effective as the cost of a machine has decreased.