You just take the disc or plans to Kinko's and tell them what size you want them printed out to. Some of the places have the percentage wheel so you don't even have to do any of that thinking stuff. If it's an 80 inch wing tell them you want it reduced down to 60 inches and they just set the little wheel at 80 then read what the percentage will be to make it 60 for you. How easy is that??