An on-demand publisher charges $22:50 to print a 600 page book and $15:50 to print a 400 page book. Find a linear function which models the cost of a book C as a function of the number of pages p. Interpret the slope of the linear function and find and interpret C(0).

Be sure to show work or an explanation with solution; generally speaking, do not just state your answer. Draw a graph if possible.