(Multiproduct firm) Elegant Books produces and sells two book products: an encyclopedia set and a dictionary set. The company sells these book sets in a ratio of three encyclopedia sets to five dictionary sets. Selling prices for the encyclopedia and dictionary sets are, respectively, $1,200 and $240; respective variable costs are $480 and $160. The company’s fixed costs are $1,800,000 per year. Compute the volume of sales of each type of book set needed to

a. break even.

b. earn $800,000 of income before tax.

c. earn $800,000 of income after tax, assuming a 30 percent tax rate.

d. earn 12 percent on sales revenue in before-tax income.

e. earn 12 percent on sales revenue in after-tax income, assuming a 30 percent tax rate.