It could be a deltahedron. A deltahedron has all faces being an equilateral triangle. The amount of faces can vary from 4, 6, 8, 10, 12, 14, 16 and 20.
The independent quantity is her pay and the dependent quantity is the hours she works in a week. I believe the range would be 30 to 35 hours and the domain would be $360 to $450.