Andrew needs to print a document that is 180 pages long. How much longer will it take to print the document on a sure fire printer than on a centroid printer

A centroid printer is a fast-print printer with a speed of 20 pages per minute. A surefire printer is also fast but it's a bit slower with a printing speed of 15 pages per minute. So,

180 pages / (20 pages per minute) - 180 / (15 pages per minute)

= 36 minutes

It would take 36 minutes faster for the centroid printer to print the document than a surefire printer.