please provide an explanation, thank you.

Pennsylvania Company supplied the following information: Direct materials $70 per unit Direct labor $5 per unit $62 per machine hour Factory overhead Number of units in Job 99 100 Direct labor hours worked on Job 99 20 Direct labor dollars spent on Job 99 $500 Machine hours used on Job 99 10 Total job cost for Job 99 is: $1,820 $8,120 $8,740 $12,620