Harris Company manufactures and sells a single product. A partially completed schedule of the company's total costs and costs per unit over the relevant range of $30,000$ to $50,000$ units is given below:

$\backslash$table$[[,$Units Produced and Sold$],[,30,000,40,000,50,000],[$Total costs:$],[$Variable cost$,$$$180,000,?,?],[$Fixed cost$,300,000,?,?],[$Total cost$,$$$480,000,?,?$