What is a monopoly and are all monopolies bad for the economy?

Which term refers to the cost that motivates an economic decision

Newton industries is considering a project and has developed the following estimates: unit sales = 4,800, price per unit = $67, variable cost per unit = $42, annual fixed costs = $11,900. the depreciation is $14,700 a year and the tax rate is 34 percent. what effect would an increase of $1 in the selling price have on the operating cash flow?

Lusk corporation produces and sells 14,300 units of product x each month. the selling price of product x is $25 per unit, and variable expenses are $19 per unit. a study has been made concerning whether product x should be discontinued. the study shows that $72,000 of the $102,000 in monthly fixed expenses charged to product x would not be avoidable even if the product was discontinued. if product x is discontinued, the annual financial advantage (disadvantage) for the company of eliminating this product should be: