Based on the information given the total cost of job #42a is $43,200.
Using this formula
Total cost of Job #42a = Direct materials + Direct labor + Predetermined overhead rate x Actual machine-hours
Let plug in the formula
Total cost of Job #42a = $18,000 + $12,000 + ($12 per machine-hour x 1,100 machine-hours)
Total cost of Job #42a= $18,000 + $12,000 +$13,200
Total cost of Job #42a= $43,200
Inconclusion the total cost of job #42a is $43,200.
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