Help me please it's due by midnight an economist modeled the demand q for a certain product as a linear function of the selling price the demand was 20000 units when the selling price was $40 per unit and the demand was 15,000 units when the selling price was $60 per unit based on the model what is a demand in unit when the selling price is $55 per unit a.15,250 b.16,500 c.16,750 d.17,500