A division of Borderland Enterprises sold 280000 financial calculators during August, 2022. The division compiled the following information:

Sales $2800000
Variable costs:
Materials $392000
Order processing 210000
Billing labor 154000
Selling expenses 84000
Total variable costs 840000
Fixed costs 1000000

What is the unit contribution margin?
a. $0.50
b. $3.00
c. $6.57
d. $7.00