The math department purchases a photocopier for $4,500. Write an equation (in y=mx+b form) to model the value of the photocopier, y, in x years if the copier's value depreciates at a constant rate of $400 per year.

Shape a is congruent to shape , as shown by a reflection across the y-axis and then a translation down units. shape b is congruent to shape , as shown by a reflection across the y-axis and then a translation down units.