Bill is shopping for folder, notebook, and pencils for the first day of school. a notebook costs 4 times as much as a folder. a notebook costs 2 times as much as a set of pencils. each folder costs $ 2 . determine the costs for 1 folder, 1 notebook, and 1 set of pencils.

So if you take the 2$ for the folder and multiply it by 4 you get the cost of the notebook 8$ the you know that a set of pencils is half the cost of a notebook so you divide 8$ by 2 and get 4. Now you know that its 2$ for  folder 8$ for a notebook and 4$ for a set of set of pencils 2$+4$+8$=14$

The vertex of the quadratic function is (1.5, -.75)