Tree Inc. sells its only product for $20. Variable cost is $7.50 per unit, and fixed cost is $5,000 per month. Required Calculate the following: (a) The contribution margin per unit The contribution margin ratio The break-even point The expected operating profit in a month when 500 units are sold (e) The number of units that need to be sold to make an operat- ing profit of $2,000 (b) (c)