A photocopy store advertises the following prices: 5/c per copy for the first 20 copies, 4/c per

copy for the 21st through 100th copy, and 3/c per copy after the 100th copy. Letxbe the

number of copies, and letybe the total cost of photocopying. (a) Graph the cost asxgoes

from 0 to 200 copies. (b) Find the equation in the formy=mx+bthat tells you the cost

of makingxcopies whenxis more than 100