How much ingredients do I need to make spaghetti for 20-25 people?

First, don't mix 2 kinds of pasta...stick to one. You will need at least 9 lbs of pasta. Make it easy on yourself and make a meatsauce instead of meat. You can make it ahead of time and just heat it up, which you can do on the griddle in a large pot. Brown 4 lbs of ground beef and spices. In a large pot heat at least 6 jars of sauce. When the beef is browned add to the sauce and simmer for about 1/2 hr. You can also pre cook the pasta. Do not cook it completely. Cut the cook time in 1/2, drain and then coat with olive oil. You can heat hot water on the griddle and finish cooking the pasta.