Why might a company claim that the total cost of employing a person is $15.30 per hour when the employee's wage rate is $10.50 per hour? How should this difference be classified and why?

What does it mean when a company has a major expense? Like for example, "The major expense for Dollar Tree Inc. is called Cost of Goods Sold, which represents the cost of the goods Dollar Tree sold to it's customers". But isn't expense a cost, it decreases net income? I did not understand this statement.

Job Costs Using a Plantwide Overhead Rate Naranjo Company designs industrial prototypes for outside companies. Budgeted overhead for the year was $225,000, and budgeted direct labor hours were 18,000. The average wage rate for direct labor is expected to be $25 per hour. During June, Naranjo Company worked on four jobs. Data relating to these four jobs follow: Job 39 Job 40 Job 41 Job 42 Beginning balance $24,300 $34,100 $17,300 $1,000 Materials requisitioned 16,100 20,000 11,300 14,100 Direct labor cost 7,200 17,100 5,950 5,000 Overhead is assigned as a percentage of direct labor cost. During June, Jobs 39 and 40 were completed; Job 39 was sold at 110 percent of cost. (Naranjo had originally developed Job 40 to order for a customer; however, that customer was near bankruptcy and the chance of Naranjo being paid was growing dimmer. Naranjo decided to hold Job 40 in inventory while the customer worked out its financial difficulties. Job 40 is the only job in Finished Goods Inventory.)…

Why must a company estimate the amount of factory overheadassigned to indivdual jobs or jobs lots