Alyssa's extended family is staying at the lake house this weekend for a family reunion. Alyssa is in charge of making homemade pancakes for the entire group. The pancake mix requires 2 cups of flour for every 10 pancakes. If Alyssa has to make 70 pancakes, how many cups of flour will Alyssa need?

If 10 pancakes require 2 cups of flour, then 70 pancakes will need 2/10*70 = <<2/10*70=14>>14 cups of flour. Answer: \boxed{14}.