George Caloz & Fr$$res$,$ located in Grenchen, Switzerland, makes luxury custom watches in small lots. One of the company's products, a platinum diving watch, goes through an etching process. The company has recorded etching costs as follows over the last six weeks:

$\backslash$table$[[$Week$,$Units,$\backslash$table$[[$Total Etching$],[$Cost$]]],[1,9,$$$25$