Direct materials cost $10 per unit, direct labour is $7 per unit, and overhead cost is applied at 130% of direct labour costs. The 6,000 units of beginning goods in progress were 100% complete as to materials, and 50% complete as to labour and overhead. The total production costs of the current period assigned to the beginning units is : a. $96,600

b. $48,300

c. $73,400

d. $54,300