Following is a list of various costs incurred in producing toy robotic helicopters. With respect to the production and sale of these toy helicopters, classify each cost as either variable, fixed, or mixed. Property taxes, $210,000 per year on factor building and equipment Janitorial costs, $5,000 per month Metal Salary of plant manager Oil used in manufacturing equipment Cost of labor for hourly workers Plastic Straight-line depreciation on the production equipment Computer chip (purchased from a vendor) Electricity costs, $0.10 per kilowatt-hour Rent on warehouse, $12,000 per month plus $20 per square foot of storage used Pension cost, $0.75 per employee hour on the job Hourly wages of machine operators Property insurance premiums, $2,000 per month plus $0,008 for each dollar of property over $1,000,000