Identify each cost below as variable, fixed, or mixed, relative to units sold. Explain your reason.

$\backslash$table$[[$Units Sold,$25,50,75,100],[$Total Phone Cost,$$250,300,350,400],[$Materials cost per unit,$$40,40,40,40],[$Manager$\text{'}$s salary,$$3,400,3,400,3,400,3,400],[$Depreciation cost per unit,$$60,30,20,15],[$Total utility cost,$$550,800,1,050,1,300],[$Total cost of goods sold,$$3,500,7,000,10,500,14,000]]$

$\backslash$table$[[$Units Sold,Cost Type,Reasoning$],[$Total cost of goods sold,Variable $,],[$Materials cost per unit,Variable $,],[$Total Phone Cost,Mixed v$,$Costs changes to # of units produced is proportional$],[$Depreciation cost per unit,Fixed v$,$Costs changes as volume changes but not proportional$],[$Manager$\text{'}$s salary,Fixed $,$Costs changes inversely proportional to # of units$],[$Total utility cost,Mixed $,$Costs do not change as volume changes$]]$