Portia Compony is a retaller of hammers. Portia pays $4.05 for each hammer and sells them for $8.45. Monthly fixed costs are $26,400. The hammer cost is the only variable cost. a. What is the contribution margin per unit? (Round your answer to 2 decimal places.) b. What is the break-even point in units? (Do not round intermediate calculations.) How many units will Portia need to sell to earn target profit of $33,880 ? (Do not round intermediate calculations.)