Answer:
producing 200 units of Model A would be the best of the 25,000 lbs of steel and 4,000 zinc available
With a profit of 200 units x $90 each = 18,000 dollars
Explanation:
Model A contribution:
90 / 125 = 0.72
90 / 20 = 4.5
Model B contribution:
70/ 100 = 0.7
70/ 30 = 2.33
As model B generates lower contribution for both scarse resources is not convinient to produced altogether.
It should produce Model A as much as it can and only fill with Model B if needed
25,000 lbs of steel / 125 per Model A = 200 units of A
200 units of A x 20 lbs of zinc each = 4,000 lbs of zinc
producing 200 units of Model A would be the best of the 25,000 lbs of steel and 4,000 zinc available