Respuesta :

c = cost
n = number of copies

Need slope first to make the linear equation: change in c / change in n = (880 - 450) / (2000 - 1000) = 430 / 1000 = 0.43 

EQUATION TIME

c = 0.43n + 20 (If you want me to go more in-depth on the equation formation just tell me)