Jon uses 7 eggs to make three omelets. How many eggs will Jon needto make 9 omelets?

Answer 1

To make 3 omelets, Jon uses 7 eggs. So, to make one omelet, Jon uses 7/3 = <<7/3=2.33>>2.33 eggs.
Therefore, to make 9 omelets, Jon will need 9 * 2.33 = <<9*2.33=20.97>>20.97 eggs.
Since he cannot use a fraction of an egg, Jon will need 21 eggs to make 9 omelets. Answer: \boxed{21}.