Identify if the following cost are usually variable, fixed, mixed, or step costs (large steps), step costs (narrow steps)

- Electricity cost, which includes a $15 per month billing charge and an additional amount depending on the number of KW used.

- A computer service agreement in which a company pays $150 per hour of technical time.

-The wages of counter help in a fast food restaurant.

- The cost of computer printers and copiers in your university.

- The salary costs of guards at a jail. Cost are set as $3600 per month if the number of prisoners is 16 or less. For every 4 additional prisoners, one additional guard must be hired at $1500 per month.

-The salary of dental hygienists in a three-dentist office. One hygienist can take care of 120 cleaning per month.

- Fuel of company's fleet of motor vehicles.

-The salary of a receptionist in a law firm.

-The cost of beer for a bar.

- Rent for a dental office.