Mark Corporation produces two models of calculators. The Business model sells for $60, and the Math model sells for $40. The variable expenses are given below:

	Business Model	Math Model
Variable production costs per unit	$15	$15
Variable selling and administrative expenses per unit	$9	$ 6

The fixed expenses are $75,600 per month. The expected monthly sales of each model are: Business, 1,000 units; Math, 500 units.

The break-even point in unit sales for the expected sales mix is closest to: (Do not round intermediate calculations.)

a. 831 Business Model and 1,662 Math Model

b. 1,662 of each product

c. 831 of each product

d. 1,662 Business Model and 831 Math Model