An airline company: The main costs in an airline company are labor and fuel costs. Labor accounts for approximately 35% of the total of airlines' operating expenses. Operating expenses account for roughly 75% of all non-fixed costs.When in a competitive business, labor costs are cut by laying off workers or reducing their pay or benefits. Other coss  are the maintenance , handling luggage , airport fees , taxes, marketing , promotion levels, travel agent commissions an d passenger expenses. As a whole, these account for nearly 55% of total operating costs.As for the cost of fuel airlines, Fuel costs account for 10% to 12% of operating expenses. Many companies have programs to hedge fuel costs. They buy futures contracts to lock in their costs for a set period of time, turning it into a fixed expense. When fuel prices rise, this behavior is rewarded. When fuel prices decline, this is punished as the market price of fuel is less than what they are paying.

A mobile phone company: Taking an example of Samsung, A phone company's operating expenses are Sellings and General Administrative expenses , and R&D Expenses. Another costs are the cost of Sales and Income Tax Expenses . 

A high school(public):Operaring a High school needs mainly staff members which is the main costs of the school(Teachers, Administrators,Concelor,Socil Supports,Instructional coaches and facilitators). The other costs that may occur are the ones related to the building itself , for example the heating, repairments and construction....) 

A hospital: The main categorieswhen it comes to hospital expenses are : 

• Wages and benefits – 56%

• Professional fees – 11.9%

• Other products, such as food, medical equipment, etc. – 11.2%

• Prescription drugs – 6.7%

• All other: labor intensive – 5.7%

• All other: non-labor intensive; includes phone and postage – 5.5%

• Professional liability insurance – 1.2%

• Utilities – 1.8%                                                                                                                                          One area where hospitals can receive significant revenues is grants, donations, bequeaths and other charitable income. For-profit hospitals might set up a tax-exempt foundation to handle gifts.In addition to the types of gains mentioned above, hospitals might also have common taxable gains such as investment income, interest earned or asset sales.

A bank: When it come to a bank , we talk about Non-interest Expenses(Noninterest expenses are the fixed operating costs of a bank (e.g., salaries and rent).and Interest Expenses . Noninterest expenses are offset by service fees such as fee income from loan originations, late charges on loans, annual fees, and credit facility fees.They are typically higher for investment banks than commercial banks because trading, asset management, and capital markets advisory services are costly.Examples of Non-Interest expenses are:

• Employee salaries, bonuses, and benefits

• Equipment rental or leasing

• Information technology (IT) costs

• Rent, telecommunication services, taxes, professional services, and marketing

As for Interest Expenses , An interest expense is the cost incurred by an entity for borrowed funds. Interest expense is a non-operating expense shown on the income statement. It represents interest payable on any borrowings – bonds, loans, convertible debt or lines of credit.