Identify whether each of the following is best described as a fixed, variable, or mixed cost with respect to product units.

$\backslash$table$[[1.$ Peanuts used in making trail mix.,$],[2.$ Taxes on factory building.,$],[3.$ Real estate taxes.,$],[4.$ Rubber used to manufacture athletic shoes.,$],[5.$ Rubber used in making tennis balls.,$],[6.$ Depreciation expense on equipment $($straight$-$line$).,],[7.$ Salesperson salary plus commission.,$]]$