Assume the following: - The variable portion of the predetermined overhead rate is $1.50 per direct labor-hour. - The standard labor-hours allowed per unit of finished goods is 3 hours. - The variable overhead rate variance is $3,000F. - The variable overhead spending variance is $4,500F. - The company produced 15,000 units of finished goods during the period. What is the actual quantity of direct labor-hours worked during the period